LGWR 대기에 따른 원인 분석 및 튜닝



 

LGWR 대기에 따른 원인 분석 및 튜닝

 

1. LGWR 기록 지연 현상

  • Disk I/O 지연으로 오라클이 대기하는 경우 발생하는 이벤트 세가지중 하나.
  • 백그라운드 프로세스의 대기 이벤트, log file parallel write(로그 파일에 로그 기록)의 시간이 길어짐.
  • 서버 프로세스의 커밋을 기다리는 이벤트, log file sync(LGWR에 기록을 요청하고 회신을 기다림)의 시간이 길어짐.

 

2. DB의 성능과 디스크I/O

  • 우선 OS성능과 I/O성능은 별개임을 알아야 합니다.
  • I/O성능은 단순하게 분석 할 수 없으며, 여러가지 상황을 고려 해야합니다.
  • 디스크는 용량이 커지다보니 사용되는 디스크의 숫자는 줄어들고 있으나, IOPS(1초당 IO횟수)는 향상되지 않아, RDBMS의 관점에서 물리적 I/O는 거의 향상되지 않습니다. 디스크의 개수가 줄어들다보니 병행액세스를 이용한 I/O성능을 향상하지 못하고, 사이즈당 I/O성능도 떨어지게 됩니다.
  • RDBMS에서 디스크에 기록할때, OS의 버퍼캐쉬, 스토리지의 캐쉬, 디스크의 캐시 순으로 기록합니다. 그렇기 때문에 OS나 스토리지, 디스크의 캐시 성능에 의해서도 속도가 좌우되며, I/O의 구조상 오라클에 가까운 계층에서 캐시에 히트할수록 고속으로 처리합니다.
  • I/O에서 특히 주의 하지않으면 안되는 것이 병렬도인데, 처리할 때 병렬도가 높아 순간적으로 큐가 생겼다가 사라짐을 반복해서 응답시간이 나빠지는 경우가 있습니다.
  • I/O지연이 발생하는 것은 오라클에서도 알수 있지만, OS에서도 반드시 정보를 수집해야 합니다. 세션수가 많거나, 대기시간이 길거나, 응답시간이 짧아도 처리량은 동일하기 때문에 RDBMS의 I/O는 인큐가 쌓여 대기시간이 늘어나도, 실제 OS에서는 I/O가 많지 않다고 나오는 경우도 있습니다.

 

3. I/O 성능의 판단

  • AWR 또는 Statspack, OS의 sar, iostat 같은 명령어를 사용하여 분석합니다.
  • log file parallel write의 경우 같은 이벤트가 v$session_wait에 반복되어 표시되므로, P1,P2,P3가 같은지 확인해서 대기 여부를 판단해야 합니다.
  • 부하가 없던 시간대의 응답시간에 비해 크게 나빠지지 않았는가 여부를 확인해야 합니다.

 

4. LGWR의 대기 원인 분석

  • AWR이나 Statspack을 통해 LGWR의 대기 이벤트가 어디에서 부터 발생하는지 찾아야 합니다.
  • 다음은 Statspack의 60분간의 top 5 time Events 입니다.
Top 5 Timed Events
~~~~~~~~~~~~~~~~~~                                    % Total
Event                        Waits          Time (s) Ela Time
--------------------------- ------------    -------- --------
log file sync                  1,350,499      27,021    50.04
db file sequential read        1,299,154      13,633    25.25
CPU time                                       7,034    13.03
io done                        3,487,217       3,225     5.97
latch free                       115,471       1,325     2.45

Statspack은 1800초 가량 돌면서, 8 CPU에서 거의 14,400 CPU seconds를 사용 할 수 있습니다. 이 서버안에 하나의 instance 만 존재한다면, CPU의 사용량은 7034/14,400 : 50% 입니다. (statspack CPU Time/total CPU time)

또 한, 60분간 log file sync가 27021 초의 대기시간을 가졌고, 27021/3600 = 7.5 평균 7.5프로세스들이 log file sync 이벤트를 발생했다. 이 것은 중심이 되는 병목현상임을 나타냅니다.

만약에 SID 3이 LGWR를 발생했다면,

SQL> select sid, event, time_waited, time_waited_micro
from v$session_event where sid=3 order by 3
/

   SID EVENT                          TIME_WAITED TIME_WAITED_MICRO
------ ------------------------------ ----------- -----------------
..
     3 control file sequential read        237848  2378480750
     3 enqueue                             417032  4170323279
     3 control file parallel write         706539  7065393146
     3 log file parallel write             768628  7686282956
     3 io done                           40822748  4.0823E+11
     3 rdbms ipc message                208478598  2.0848E+12

rdbms ipc message가 가장 높게 나타나지만 일반적으로 무시할 수 있는 이벤트이고, 그 다음으로 높게 나타난 io done의 경우 LGWR의 I/O call complete와 LGWR의 기록이 동기식 기록를 하고난 후의 비동기식 I/O요청입니다.

oracle session snapper.sql 을 이용하면 SID 3 세션의 1초동안 일어난 LGWR을 확인할 수 있습니다.

------------------------------------------------------------------
SID, SNAPSHOT START  ,SEC, TYPE, STATISTIC            ,    DELTA,
------------------------------------------------------------------
3, 20080513 11:44:32,   1, STAT, messages sent        ,        9,
3, 20080513 11:44:32,   1, STAT, messages received    ,      153,
3, 20080513 11:44:32,   1, STAT, redo wastage         ,    39648,
3, 20080513 11:44:32,   1, STAT, redo writes          ,      152,
3, 20080513 11:44:32,   1, STAT, redo blocks written  ,     1892,
3, 20080513 11:44:32,   1, STAT, redo write time      ,       82,
3, 20080513 11:44:32,   1, WAIT, rdbms ipc message    ,   169504,
3, 20080513 11:44:32,   1, WAIT, io done              ,   813238,
3, 20080513 11:44:32,   1, WAIT, log file parallel write ,  5421,
3, 20080513 11:44:32,   1, WAIT, LGWR wait for redo copy ,     1,

아니면 Level 12의 10046 trace를 통해 확인 할 수 있습니다.

WAIT #0: nam='rdbms ipc message' ela= 7604 p1=223 p2=0 p3=0
WAIT #0: nam='log file parallel write' ela= 35 p1=2 p2=16 p3=2
WAIT #0: nam='io done' ela= 0 p1=0 p2=0 p3=0
WAIT #0: nam='io done' ela= 639 p1=0 p2=0 p3=0
WAIT #0: nam='io done' ela= 0 p1=0 p2=0 p3=0
WAIT #0: nam='io done' ela= 605 p1=0 p2=0 p3=0
WAIT #0: nam='io done' ela= 1 p1=0 p2=0 p3=0
WAIT #0: nam='io done' ela= 366 p1=0 p2=0 p3=0

다음은 Statspack의 특정 컬럼만을 조회한 항목입니다.

Statistic                             Total     per Second
------------------------------- ----------- --------------
redo blocks written                 230,881        2,998.5
redo buffer allocation retries            0            0.0
redo entries                        285,803        3,711.7
redo log space requests                   0            0.0
redo log space wait time                  0            0.0
redo ordering marks                       0            0.0
redo size                       109,737,304    1,425,159.8
redo synch time                      40,744          529.1
redo synch writes                    38,141          495.3
redo wastage                      5,159,124       67,001.6
redo write time                       6,226           80.9
redo writer latching time                 4            0.1
user calls                          433,717        5,632.7
user commits                         38,135          495.3
user rollbacks                            1            0.0
workarea executions - multipass           0            0.0
  1. 5,632 user calls / 495.3 user commits 의 값으로 초당 실행시간 평균을 구할 수 있다.
  2. LGWR에 의해 3000 redo block 을 썼다는 걸 알수 있는데, 솔라리스처럼 1block에 512bytes라면 초당 1.5mb/s 인것이다.
  3. redo가 1.4mb/s로 갱신 된다면 16mbps에 근접한다.
  4. 3000 redo block에서 38,155 commit이 일어났다.

위의 redo 사이즈는 일반적으로 작은 사이즈가 아니지만, 초당 500 commit을 처리하기 위해서는 더 커야합니다.

적절한 사이즈의 redo 인가 확인 한 후, 다음으로 고려해야 할 사항은 CPU에 의한 LGWR 대기 현상입니다.

commit 빈도 확인을 하고, 높다면 foreground 프로세스에서 일어나는 log file sync 이벤트만을 찾아 OS에서 LGWR의 CPU사용량을 체크합니다.

그 다음은 아주 적게 발생하는 것중 하나인데, 인스턴스 프리징현상이 있는 경우 v$sysstat을 20초 간격으로 캡쳐하고, Oracle-supplied tool, LTOM을 이용하여 iostat를 캡쳐 합니다.

23-MAR-2007-04:29:43:Redo blocks written:1564176614:Delta: 8253
23-MAR-2007-04:30:14:Redo blocks written:1564176614:Delta:    0
23-MAR-2007-04:30:44:Redo blocks written:1564205771:Delta:29157

위와 같이 Commit 처리량이나, redo 사이즈 CPU사용량에 영향이 없음에도 log file parallel write, log file sync 가 크게 나타난다면 하드웨어의 I/O문제라고 파악 할 수 있습니다.

r/s  w/s kr/s kw/s wait actv wsvc_t asvc_t %w  %b device
0.0  0.0  0.0  0.0  0.0  1.0    0.0    0.0  0 100 d6
0.0  0.0  0.0  0.0  0.0  1.0    0.0    0.0  0 100 d2
0.0  0.0  0.0  0.0  0.0  1.0    0.0    0.0  0 100 d1
0.0  0.0  0.0  0.0  0.0  9.0    0.0    0.0  0 100 d0
0.0  0.0  0.0  0.0  0.0  3.0    0.0    0.0  0 100 d13
0.0  2.0  0.0 24.0  0.0  2.0    0.0 1000.7  0 100 d12
0.0  0.0  0.0  0.0  0.0  1.0    0.0    0.0  0 100 d11

%b는 I/O가 디스크에 의존한 %를 알려주는데 요즘엔 디스크의 여러 이유로 인해 Busy%를 전적으로 신뢰 할 수 없습니다.

r/s reads per second
w/s writes per second
Kr/s kilobytes read per second
Kw/s kilobytes written per second
wait average number of transactions waiting for service (queue length)
actv average number of transactions actively being serviced (removed from the queue but not yet completed)
svc_t average service time, in milliseconds
%w percent of time there are transactions waiting for service (queue non-empty)
%b percent of time the disk is busy (transactions in progress)
wsvc_t average service time in wait queue, in milliseconds
asvc_t average service time active transactions, inmilliseconds

I/O를 체크했을때 LGWR이 발생할 당시 I/O의 속도가 15ms 보다 크게 나온다면 디스크 속도가 떨어진다고 할 수 있습니다.

I/O자체가 늦어 LGWR에 대기가 발생하는 경우는 I/O 대역폭을 올려 해결 하는 수 밖에 없습니다.

OS와 스토리지 간의 지연을 찾거나, 그밖의 디스크I/O문제, 여러 상황을 고려하고 문제를 풀어나가야 합니다.

스토리지 cache의 히트율이나, OS버퍼 cache의 영향도 고려 해야 하기 때문에 단순히 RDBMS 엔지니어 혼자 판단하기는 쉽지 않습니다.

 

log_file_sync_check.sql

Slow disk I/O:  Segregating the redo log file onto separate disk spindles can reduce log file sync waits. Moving the online redo logs to fast SSD storage and increasing the log_buffer size above 10 megabytes (It is automatically set in 11g and beyond).  If I/O is slow (timings in AWR or STATSPACK reports > 15 ms), then the only solution for log file sync waits is to improve I/O bandwidth.
 
 
set echo off
set feedback off
column timecol new_value timestamp
column spool_extension new_value suffix
select to_char(sysdate,'Mondd_hh24mi') timecol,
'.out' spool_extension from sys.dual;
column output new_value dbname
select value || '_' output
from v$parameter where name = 'db_name';
spool lfsdiag_&&dbname&&timestamp&&suffix
set trim on
set trims on
set lines 130
set pages 100
set verify off
alter session set optimizer_features_enable = '10.2.0.4';

PROMPT LFSDIAG DATA FOR &&dbname&&timestamp
PROMPT Note: All timings are in milliseconds (1000 milliseconds = 1 second)

PROMPT
PROMPT IMPORTANT PARAMETERS RELATING TO LOG FILE SYNC WAITS:
column name format a40 wra
column value format a40 wra
select inst_id, name, value from gv$parameter
where ((value is not null and name like '%log_archive%') or
name like '%commit%' or name like '%event=%' or name like '%lgwr%')
and name not in (select name from gv$parameter where (name like '%log_archive_dest_state%'
and value = 'enable') or name = 'log_archive_format')
order by 1,2,3;

PROMPT
PROMPT HISTOGRAM DATA FOR LFS AND OTHER RELATED WAITS:
PROMPT
PROMPT APPROACH: Look at the wait distribution for log file sync waits
PROMPT by looking at "wait_time_milli". Look at the high wait times then
PROMPT see if you can correlate those with other related wait events.
column event format a40 wra
select inst_id, event, wait_time_milli, wait_count
from gv$event_histogram
where event in ('log file sync','gcs log flush sync',
'log file parallel write','wait for scn ack',
'log file switch completion','gc cr grant 2-way',
'gc buffer busy','gc current block 2-way') or
event like '%LGWR%' or event like '%LNS%'
order by 2 desc,1,3;

PROMPT
PROMPT ORDERED BY WAIT_TIME_MILLI
select inst_id, event, wait_time_milli, wait_count
from gv$event_histogram
where event in ('log file sync','gcs log flush sync',
'log file parallel write','wait for scn ack',
'log file switch completion','gc cr grant 2-way',
'gc buffer busy','gc current block 2-way')
or event like '%LGWR%' or event like '%LNS%'
order by 3,1,2 desc;

PROMPT
PROMPT REDO WRITE STATS
PROMPT
PROMPT "redo write time" in centiseconds (100 per second)
PROMPT 11.1: "redo write broadcast ack time" in centiseconds (100 per second)
PROMPT 11.2: "redo write broadcast ack time" in microseconds (1000 per millisecond)
column value format 99999999999999999999
column milliseconds format 99999999999999.999
select v.version, ss.inst_id, ss.name, ss.value,
decode(substr(version,1,4),
'11.1',decode (name,'redo write time',value*10,
'redo write broadcast ack time',value*10),
'11.2',decode (name,'redo write time',value*10,
'redo write broadcast ack time',value/1000),
decode (name,'redo write time',value*10)) milliseconds
from gv$sysstat ss, v$instance v
where name like 'redo write%' and value > 0
order by 1,2,3;

PROMPT
PROMPT ASH THRESHOLD...
PROMPT
PROMPT This will be the threshold in milliseconds for average log file sync
PROMPT times. This will be used for the next queries to look for the worst
PROMPT 'log file sync' minutes. Any minutes that have an average log file
PROMPT sync time greater than the threshold will be analyzed further.
column threshold_in_ms new_value threshold format 999999999.999
select min(threshold_in_ms) threshold_in_ms
from (select inst_id, to_char(sample_time,'Mondd_hh24mi') minute,
avg(time_waited)/1000 threshold_in_ms
from gv$active_session_history
where event = 'log file sync'
group by inst_id,to_char(sample_time,'Mondd_hh24mi')
order by 3 desc)
where rownum <= 5;

PROMPT
PROMPT ASH WORST MINUTES FOR LOG FILE SYNC WAITS:
PROMPT
PROMPT APPROACH: These are the minutes where the avg log file sync time
PROMPT was the highest (in milliseconds).
column event format a30 tru
column program format a35 tru
column total_wait_time format 999999999999.999
column avg_time_waited format 999999999999.999
select to_char(sample_time,'Mondd_hh24mi') minute, inst_id, event,
sum(time_waited)/1000 TOTAL_WAIT_TIME , count(*) WAITS,
avg(time_waited)/1000 AVG_TIME_WAITED
from gv$active_session_history
where event = 'log file sync'
group by to_char(sample_time,'Mondd_hh24mi'), inst_id, event
having avg(time_waited)/1000 > &&threshold
order by 1,2;

PROMPT
PROMPT ASH LFS BACKGROUND PROCESS WAITS DURING WORST MINUTES:
PROMPT
PROMPT APPROACH: What is LGWR doing when 'log file sync' waits
PROMPT are happening? LMS info may be relevent for broadcast
PROMPT on commit and LNS data may be relevant for dataguard.
PROMPT If more details are needed see the ASH DETAILS FOR WORST
PROMPT MINUTES section at the bottom of the report.
column inst format 999
column event format a30 tru
column program format a35 wra
select to_char(sample_time,'Mondd_hh24mi') minute, inst_id inst, program, event,
sum(time_waited)/1000 TOTAL_WAIT_TIME , count(*) WAITS,
avg(time_waited)/1000 AVG_TIME_WAITED
from gv$active_session_history
where to_char(sample_time,'Mondd_hh24mi') in (select to_char(sample_time,'Mondd_hh24mi')
from gv$active_session_history
where event = 'log file sync'
group by to_char(sample_time,'Mondd_hh24mi'), inst_id
having avg(time_waited)/1000 > &&threshold)
and (program like '%LGWR%' or program like '%LMS%' or
program like '%LNS%' or event = 'log file sync')
group by to_char(sample_time,'Mondd_hh24mi'), inst_id, program, event
order by 1,2,3,5 desc, 4;

PROMPT
PROMPT AWR WORST AVG LOG FILE SYNC SNAPS:
PROMPT
PROMPT APPROACH: These are the AWR snaps where the average 'log file sync'
PROMPT times were the highest.
column begin format a12 tru
column end format a12 tru
column name format a13 tru
select dhs.snap_id, dhs.instance_number inst, to_char(dhs.begin_interval_time,'Mondd_hh24mi') BEGIN,
to_char(dhs.end_interval_time,'Mondd_hh24mi') END,
en.name, se.time_waited_micro/1000 total_wait_time, se.total_waits,
se.time_waited_micro/1000 / se.total_waits avg_time_waited
from dba_hist_snapshot dhs, wrh$_system_event se, v$event_name en
where (dhs.snap_id = se.snap_id and dhs.instance_number = se.instance_number)
and se.event_id = en.event_id and en.name = 'log file sync' and
dhs.snap_id in (select snap_id from (
select se.snap_id, se.time_waited_micro/1000 / se.total_waits avg_time_waited
from wrh$_system_event se, v$event_name en
where se.event_id = en.event_id and en.name = 'log file sync'
order by avg_time_waited desc)
where rownum < 4)
order by 1,2;

PROMPT
PROMPT AWR REDO WRITE STATS
PROMPT
PROMPT "redo write time" in centiseconds (100 per second)
PROMPT 11.1: "redo write broadcast ack time" in centiseconds (100 per second)
PROMPT 11.2: "redo write broadcast ack time" in microseconds (1000 per millisecond)
column stat_name format a30 tru
select v.version, ss.snap_id, ss.instance_number inst, sn.stat_name, ss.value,
decode(substr(version,1,4),
'11.1',decode (stat_name,'redo write time',value*10,
'redo write broadcast ack time',value*10),
'11.2',decode (stat_name,'redo write time',value*10,
'redo write broadcast ack time',value/1000),
decode (stat_name,'redo write time',value*10)) milliseconds
from wrh$_sysstat ss, wrh$_stat_name sn, v$instance v
where ss.stat_id = sn.stat_id
and sn.stat_name like 'redo write%' and ss.value > 0
and ss.snap_id in (select snap_id from (
select se.snap_id, se.time_waited_micro/1000 / se.total_waits avg_time_waited
from wrh$_system_event se, v$event_name en
where se.event_id = en.event_id and en.name = 'log file sync'
order by avg_time_waited desc)
where rownum < 4)
order by 1,2,3;

PROMPT
PROMPT AWR LFS AND OTHER RELATED WAITS FOR WORST LFS AWRs:
PROMPT
PROMPT APPROACH: These are the AWR snaps where the average 'log file sync'
PROMPT times were the highest. Look at related waits at those times.
column name format a40 tru
select se.snap_id, se.instance_number inst, en.name,
se.total_waits, se.time_waited_micro/1000 total_wait_time,
se.time_waited_micro/1000 / se.total_waits avg_time_waited
from wrh$_system_event se, v$event_name en
where se.event_id = en.event_id and (en.name in
('log file sync','gcs log flush sync',
'log file parallel write','wait for scn ack',
'log file switch completion','gc cr grant 2-way',
'gc buffer busy','gc current block 2-way')
or en.name like '%LGWR%' or en.name like '%LNS%')
and se.snap_id in (select snap_id from (
select se.snap_id, se.time_waited_micro/1000 / se.total_waits avg_time_waited
from wrh$_system_event se, v$event_name en
where se.event_id = en.event_id and en.name = 'log file sync'
order by avg_time_waited desc)
where rownum < 4)
order by 1, 6 desc;

PROMPT
PROMPT AWR HISTOGRAM DATA FOR LFS AND OTHER RELATED WAITS FOR WORST LFS AWRs:
PROMPT Note: This query won't work on 10.2 - ORA-942
PROMPT
PROMPT APPROACH: Look at the wait distribution for log file sync waits
PROMPT by looking at "wait_time_milli". Look at the high wait times then
PROMPT see if you can correlate those with other related wait events.
select eh.snap_id, eh.instance_number inst, en.name, eh.wait_time_milli, eh.wait_count
from wrh$_event_histogram eh, v$event_name en
where eh.event_id = en.event_id and
(en.name in ('log file sync','gcs log flush sync',
'log file parallel write','wait for scn ack',
'log file switch completion','gc cr grant 2-way',
'gc buffer busy','gc current block 2-way')
or en.name like '%LGWR%' or en.name like '%LNS%')
and snap_id in (select snap_id from (
select se.snap_id, se.time_waited_micro/1000 / se.total_waits avg_time_waited
from wrh$_system_event se, v$event_name en
where se.event_id = en.event_id and en.name = 'log file sync'
order by avg_time_waited desc)
where rownum < 4)
order by 1,3 desc,2,4;

PROMPT
PROMPT ORDERED BY WAIT_TIME_MILLI
PROMPT Note: This query won't work on 10.2 - ORA-942
select eh.snap_id, eh.instance_number inst, en.name, eh.wait_time_milli, eh.wait_count
from wrh$_event_histogram eh, v$event_name en
where eh.event_id = en.event_id and
(en.name in ('log file sync','gcs log flush sync',
'log file parallel write','wait for scn ack',
'log file switch completion','gc cr grant 2-way',
'gc buffer busy','gc current block 2-way')
or en.name like '%LGWR%' or en.name like '%LNS%')
and snap_id in (select snap_id from (
select se.snap_id, se.time_waited_micro/1000 / se.total_waits avg_time_waited
from wrh$_system_event se, v$event_name en
where se.event_id = en.event_id and en.name = 'log file sync'
order by avg_time_waited desc)
where rownum < 4)
order by 1,4,2,3 desc;

PROMPT
PROMPT ASH DETAILS FOR WORST MINUTES:
PROMPT
PROMPT APPROACH: If you cannot determine the problem from the data
PROMPT above, you may need to look at the details of what each session
PROMPT is doing during each 'bad' snap. Most likely you will want to
PROMPT note the times of the high log file sync waits, look at what
PROMPT LGWR is doing at those times, and go from there...
column program format a45 wra
column sample_time format a25 tru
column event format a30 tru
column time_waited format 999999.999
column p1 format a40 tru
column p2 format a40 tru
column p3 format a40 tru
select sample_time, inst_id inst, session_id, program, event, time_waited/1000 TIME_WAITED,
p1text||': '||p1 p1,p2text||': '||p2 p2,p3text||': '||p3 p3
from gv$active_session_history
where to_char(sample_time,'Mondd_hh24mi') in (select
to_char(sample_time,'Mondd_hh24mi')
from gv$active_session_history
where event = 'log file sync'
group by to_char(sample_time,'Mondd_hh24mi'), inst_id
having avg(time_waited)/1000 > &&threshold)
order by 1,2,3,4,5;

select to_char(sysdate,'Mondd hh24:mi:ss') TIME from dual;

spool off

PROMPT
PROMPT OUTPUT FILE IS: lfsdiag_&&dbname&&timestamp&&suffix
PROMPT

 

oracle_session_snapper.sql

----------------------------------------------------------------------------
--
-- File name:   snapper.sql (Oracle Session Snapper v4)
-- Purpose:     An easy to use Oracle session-level performance measurement tool
--              which does NOT require any database changes nor creation of any
--              database objects!
--
--              This is very useful for ad-hoc performance diagnosis in environments
--              with restrictive change management processes, where creating
--              even temporary tables and PL/SQL packages is not allowed or would
--              take too much time to get approved.
--
--              All processing is done by a few sqlplus commands and an anonymous
--              PL/SQL block, all that's needed is SQLPLUS access (and if you want
--              to output data to server-side tracefile then execute rights on
--              DBMS_SYSTEM). Snapper only queries some V$ views (and in advanced
--              mode some X$ fixed tables, but it does not enable any traces nor
--              use oradebug.
--
--              The output is formatted the way it could be easily post-processed
--              by either Unix string manipulation tools or loaded to spreadsheet.
--
--              Snapper v4.20 Oracle 12c CDB and PDB grouping
--              Snapper v4 supports RAC and requires Oracle 10.1 or a newer DB version.
--              Snapper v3.5 works on Oracle versions starting from Oracle 9.2 (no RAC support)
--
-- Note1:       The "ASH" functionality in Snapper just samples GV$SESSION view,
--              so you do NOT need Diagnostics Pack licenses to use Snapper's
--              "ASH" output
--
-- Note2:       Snapper just reports you performance metric deltas in a snapsphot
--              and does not attempt to solve any performance problems for you.
--              You still need to interpret and understand these standard Oracle
--              metrics yourself
--
-- Author:      Tanel Poder (tanel@tanelpoder.com)
-- Copyright:   (c) Tanel Poder - http://blog.tanelpoder.com - All rights reserved.
--
-- Disclaimer:  This script is provided "as is", so no warranties or guarantees are
--              made about its correctness, reliability and safety. Use it at your
--              own risk!
--
-- License:     1) You may use this script for your (or your businesses) purposes for free
--              2) You may modify this script as you like for your own (or your businesses) purpose,
--                 but you must always leave this script header (the entire comment section), including the
--                 author, copyright and license sections as the first thing in the beginning of this file
--              3) You may NOT publish or distribute this script or any variation of it PUBLICLY
--                 (including, but not limited to uploading it to your public website or ftp server),
--                 instead just link to its location in blog.tanelpoder.com
--              4) You may distribute this script INTERNALLY in your company, for internal use only,
--                 for example when building a standard DBA toolset to be deployed to all
--                 servers or DBA workstations 
--
--
-- Thanks to:   Adrian Billington, Jamey Johnston, Marcus Mönnig, Hans-Peter Sloot,
--              Ronald Rood and Peter Bach for bugfixes, additions and improvements
--
--------------------------------------------------------------------------------
--
--   The Session Snapper v4.24 ( USE AT YOUR OWN RISK !!! )
--   (c) Tanel Poder ( http://blog.tanelpoder.com )
--
--
--    +-----=====O=== Welcome to The Session Snapper! (Yes, you are looking at a cheap ASCII
--   /                                                 imitation of a fish and a fishing rod.
--   |                                                 Nevertheless the PL/SQL code below the
--   |                                                 fish itself should be helpful for quick
--   |                                                 catching of relevant Oracle performance
--   |                                                 information.
--   |                                                 So I wish you happy... um... snapping?
--   |                                                )
--   |                       ......
--   |                       iittii,,....
--   ¿                    iiffffjjjjtttt,,
--                ..;;ttffLLLLffLLLLLLffjjtt;;..
--            ..ttLLGGGGGGLLffLLLLLLLLLLLLLLffjjii,,                        ..ii,,
--            ffGGffLLLLLLjjttjjjjjjjjffLLLLLLLLLLjjii..                ..iijj;;....
--          ffGGLLiittjjttttttiittttttttttffLLLLLLGGffii..            ;;LLLLii;;;;..
--        ffEEGGffiittiittttttttttiiiiiiiittjjjjffLLGGLLii..      iiLLLLLLttiiii,,
--      ;;ffDDLLiiiitt,,ttttttttttttiiiiiiiijjjjjjffLLLLffttiiiiffLLGGLLjjtttt;;..
--    ..ttttjjiitt,,iiiiiittttttttjjjjttttttttjjjjttttjjttttjjjjffLLDDGGLLttii..
--    iittiitttt,   ;;iittttttttjjjjjjjjjjttjjjjjjffffffjjjjjjjjjjLLDDGGLLtt;;..
--    jjjjttttii:. ..iiiiffLLGGLLLLLLLLffffffLLLLLLLLLLLLLLLLffffffLLLLLLfftt,,
--    iittttii,,;;,,ttiiiiLLLLffffffjjffffLLLLLLLLffLLffjjttttttttttjjjjffjjii..
--    ,,iiiiiiiiiittttttiiiiiiiiiijjffffLLLLLLLLffLLffttttttii;;;;iiiitttttttt;;..
--    ..iittttttffffttttiiiiiiiiiittttffjjjjffffffffttiittii::    ....,,;;iittii;;
--      ..;;iittttttttttttttttiiiiiittttttttttjjjjjjtttttt;;              ..;;ii;;..
--          ..;;;;iittttttjjttiittttttttttttttjjttttttttii..                  ....
--                ....;;;;ttjjttttiiiiii;;;;;;iittttiiii..
--                      ..;;ttttii;;....      ..;;;;....
--                        ..iiii;;..
--                          ..;;,,
--                            ....
--
--
--  Usage:
--
--      snapper.sql <ash[1-3]|stats|all>[,out][,trace][,pagesize=X][,gather=[s][t][w][l][e][b][a]]> <seconds_in_snap> <snapshot_count> <sid(s)_to_snap>
--
--          ash      - sample session activity ASH style, waits and SQL_IDs from gv$session and
--                     print a TOP SQL/wait report from these samples (this is the default from
--                     Snapper 3.0). The columns chosen for TOP calculation are defined in CONFIG
--                     section below.
--
--          ash=sql_id+event+wait_class
--                   - the above example illustrates that you can also specify the gv$session
--                     columns for TOP report yourself. The above example will show a TOP
--                     activity report grouped by SQL_ID + EVENT + WAIT_CLASS
--                     Note that the columns are separated by a "+" sign (as comma is a snapper 
--                     parameter separator, not ASH column separator)
--
--          ash1
--          ash2
--          ash3     - in addition to "ash" report you can have 3 more reported during the same
--                     snapper sampling snapshot. Just include ash1=col1+col2,ash2=col3+col4,...
--                     parameters if you want multiple TOP reports per Snapper snapshot
--
--          stats    - sample gv$sesstat,gv$sess_time_model,gv$session_event performance counters
--                     and report how much these stats increased (deltas) during Snapper run
--          all      - report both ASH and stats sections
--
--          out      - use dbms_output.put_line() for output. output will be seen only when
--                     Snapper run completes due to dbms_output limitations. This is the default.
--          trace    - write output to server process tracefile
--                     (you must have execute permission on sys.dbms_system.ksdwrt() for that,
--                      you can use both out and trace parameters together if you like )
--
--          pagesize - display header lines after X snapshots. if pagesize=0 don't display
--                     any headers. pagesize=-1 will display a terse header only once
--
--          gather   - if omitted, gathers s,t,w statistics (see below)
--                   - if specified, then gather following:
--
--                        Session-level stats:
--                          s - Session Statistics from gv$sesstat
--                          t - Session Time model info from gv$sess_time_model
--                          w - Session Wait statistics from gv$session_event and gv$session_wait
--
--                        Instance-level stats:
--                          l - instance Latch get statistics ( gets + immediate_gets )
--                          e - instance Enqueue lock get statistics
--                          b - buffer get Where statistics -- useful in versions up to 10.2.x
--                          a - All above
--
--          sinclude - if specified, then show only GV$SESSTAT stats which match the
--                     LIKE pattern of sinclude (REGEXP_LIKE in 10g+)
--          linclude - if specified, then show only GV$LATCH latch stats which match the
--                     LIKE pattern of linclude (REGEXP_LIKE in 10g+)
--          tinclude - if specified, then show only GV$SESS_TIME_MODEL stats which match the
--                     LIKE pattern of tinclude (REGEXP_LIKE in 10g+)
--          winclude - if specified, then show only GV$SESSION_EVENT wait stats which match the
--                     LIKE pattern of winclude (REGEXP_LIKE in 10g+)
--
--          you can combine above parameters in any order, separate them by commas
--          !!!don't use spaces as otherwise they are treated as next parameters by sqlplus   !!!
--          !!!if you want to use spaces, enclose the whole sqlplus parameter in doublequotes !!!
--
--      <seconds_in_snap> - the number of seconds between taking snapshots
--      <snapshot_count>  - the number of snapshots to take ( maximum value is power(2,31)-1 )
--
--      <sids_to_snap> can be either one sessionid, multiple sessionids separated by
--      commas or a SQL statement which returns a list of SIDs (if you need spaces
--      in that parameter text, enclose it in double quotes).
--
--      if you want to snap ALL sids, use "all" as value for
--      <sids_to_snap> parameter
--
--      alternatively you can use "select sid from gv$session" as value for <sids_to_snap>
--      parameter to capture all SIDs. you can write any query (with multiple and/or)
--      conditions to specify complex rules for capturing only the SIDs you want
--
--      starting from version 3.0 there are further session_id selection options available in 
--      instead of sid you can write such expressions for snapper's <sids_to_snap> parameter:
--
--         sid=123     -- take sid 123 only (the same as just writing 123)
--         user=tanel  -- take all sessions where username is 'tanel' (case insensitive)
--                     -- this is the same as writing following subquery for the 
--                     -- <sids_to_snap> parameter:
--                            select sid from gv$session where lower(username) like lower('tanel')
--                     
--         user=tanel% -- take all sessions where username begins with 'tanel%' (case insensitive)
--                     -- the = means actually LIKE in SQL terms in this script
-- 
--          spid=1234  -- all these 3 parameters do the same thing:
--          ospid=1234 -- they look up the sessions(s) where the processes OS PID=1234
--          pid=1234   -- this is useful for quickly looking up what some OS process is doing
--                     -- if it consumes too much of some resource
--          qc=123     
--          qcsid=123  -- show query coordinator and all PX slave sessions
--
--         program=sqlplus%     -- the following examples filter by corresponding gv$session coulmns 
--         machine=linux01      -- machine
--         osuser=oracle        -- os username
--         module=HR            -- module
--         "action=Find Order"  -- note the quotes because there is a space inside the parameter
--                              -- value
--         client_id=tanelpoder -- show only sessions where client_identifier is set to tanelpoder
--                              -- this is very useful in cases with (properly instrumented)
--                              -- connection pools
--
--
--      Note that if you want to change some "advanced" snapper configuration parameters
--      or default values then search for CONFIG in this file to see configurable
--      variable section
--
--
--  Examples:
--      NB! Read the online examples, these are more detailed and list script output too!
--
--          http://tech.e2sn.com/oracle-scripts-and-tools/session-snapper
--
--      @snapper ash,stats 1 1 515
--      (Output one 1-second snapshot of session 515 using dbms_output and exit
--       Wait, gv$sesstat and gv$sess_time_model statistics are reported by default
--       Starting from V3 the ASH style session activity report is shown as well)
--
--      @snapper stats,gather=w 1 1 515
--      (Output one 1-second snapshot of session 515 using dbms_output and exit
--       only Wait event statistics are reported, no ASH)
--
--      @snapper ash,gather=st 1 1 515
--      (Output one 1-second snapshot of session 515 using dbms_output and exit
--       only gv$sesstat and gv$sess_Time_model statistics are gathered + ASH)
--
--      @snapper trace,ash,gather=stw,pagesize=0 10 90 117,210,313
--      (Write 90 10-second snapshots into tracefile for session IDs 117,210,313
--       all statistics are reported, do not print any headers)
--
--      @snapper trace,ash 900 999999999 "select sid from v$session"
--      (Take a snapshot of ALL sessions every 15 minutes and write the output to trace,
--       loop (almost) forever )
--
--      @snapper out,trace 300 12 "select sid from v$session where username='APPS'"
--      (Take 12 5-minute snapshots of all sessions belonging to APPS user, write
--       output to both dbms_output and tracefile)
--
--  Notes:
--
--      Snapper does not currently detect if a session with given SID has
--      ended and been recreated between snapshots, thus it may report bogus
--      statistics for such sessions. The check and warning for that will be
--      implemented in a future version.
--
--------------------------------------------------------------------------------

set termout off tab off verify off linesize 999 trimspool on trimout on null ""

--debug:
-- set termout on serveroutput on

-- Get parameters (future snapper v4.x extended syntax: @snapper <options> <"begin"|"end"|sleep#> <"snap_name"|snap_count> <sid>)
define snapper_options="&1"
define   snapper_sleep="&2"
define   snapper_count="&3"
define     snapper_sid="&4"


-- The following code is required for making this script "dynamic" as due to
-- different Oracle versions, script parameters or granted privileges some
-- statements might not compile if not adjusted properly.

define _IF_ORA12_OR_HIGHER="--"
define _IF_LOWER_THAN_ORA12="--"
define _IF_ORA11_OR_HIGHER="--"
define _IF_LOWER_THAN_ORA11="--"
define _IF_DBMS_SYSTEM_ACCESSIBLE="/* dbms_system is not accessible" 
-- /*dummy*/ -- this "dummy" is here just for avoiding VIM syntax highlighter going crazy due to previous line
define _IF_X_ACCESSIBLE="--"

-- plsql_object_id columns available in v$session (from 10.2.0.3)
define _YES_PLSQL_OBJ_ID="--"  
define _NO_PLSQL_OBJ_ID=""
-- blocking_instance available in v$session (from 10.2)
define _YES_BLK_INST="--"      
define _NO_BLK_INST=""

-- snapper v4 manual before/after snapshotting
define _MANUAL_SNAPSHOT="--"   
define _USE_DBMS_LOCK=""

-- set the noprint's value to "noprint" if you don't want these temporary variables to show up in a sqlplus spool file
-- however, setting noprint="noprint" can cause errors in Oracle SQL Developer v4.0.x for some reason (OK in v4.1)
DEF noprint=""
col snapper_ora12higher    &noprint new_value _IF_ORA12_OR_HIGHER
col snapper_ora12lower     &noprint new_value _IF_LOWER_THAN_ORA12
col snapper_ora12          &noprint new_value _IF_ORA12_OR_HIGHER
col snapper_ora11higher    &noprint new_value _IF_ORA11_OR_HIGHER
col snapper_ora11lower     &noprint new_value _IF_LOWER_THAN_ORA11
col dbms_system_accessible &noprint new_value _IF_DBMS_SYSTEM_ACCESSIBLE
col x_accessible           &noprint new_value _IF_X_ACCESSIBLE
col no_plsql_obj_id        &noprint new_value _NO_PLSQL_OBJ_ID
col yes_plsql_obj_id       &noprint new_value _YES_PLSQL_OBJ_ID
col no_blk_inst            &noprint new_value _NO_BLK_INST
col yes_blk_inst           &noprint new_value _YES_BLK_INST
col manual_snapshot        &noprint new_value _MANUAL_SNAPSHOT
col use_dbms_lock          &noprint new_value _USE_DBMS_LOCK

col snapper_sid            &noprint new_value snapper_sid

-- sid_filter and inst_filter are the new RAC gv$ friendly way to filter sessions in Snapper v4 
def sid_filter="/**/"
def inst_filter="/**/"
col sid_filter             &noprint new_value sid_filter
col inst_filter            &noprint new_value inst_filter


-- initialize, precompute and determine stuff
var v                      varchar2(100)
var x                      varchar2(10)
var sid_filter             varchar2(4000)
var inst_filter            varchar2(4000)

-- this is here for a reason
-- im extracting the first word of the snapper_sid (if its a complex expression, not just a single SID)
-- by relying on how DEF and & assignment treat spaces in strings
def ssid_begin=&snapper_sid

declare

    o                      sys.dbms_describe.number_table;
    p                      sys.dbms_describe.number_table;
    l                      sys.dbms_describe.number_table;
    a                      sys.dbms_describe.varchar2_table;
    dty                    sys.dbms_describe.number_table;
    def                    sys.dbms_describe.number_table;
    inout                  sys.dbms_describe.number_table;
    len                    sys.dbms_describe.number_table;
    prec                   sys.dbms_describe.number_table;
    scal                   sys.dbms_describe.number_table;
    rad                    sys.dbms_describe.number_table;
    spa                    sys.dbms_describe.number_table;

    tmp                    number;
    lv_sid_filter          varchar2(4000);
    lv_inst_filter         varchar2(4000);

    function get_filter(str in varchar2) return varchar2
    is
      ret varchar2(1000);
    begin
      if str like '%@%' then 
        --dbms_output.put_line('get_filter:1 str= '||str);
        ret := lower(trim(regexp_replace(substr(str,instr(str,'=')+1), '^(.+)@([[:digit:]\*]+)(.*)', '\1')));
      else
        --dbms_output.put_line('get_filter:2 str= '||str);
        ret := lower(trim(substr(str,instr(str,'=')+1)));
      end if;
      --dbms_output.put_line('get_filter = ' || ret);
      return ret;
    end get_filter;

begin
    -- compute inst_filter
    case 
        when regexp_instr('&ssid_begin','@')           = 0 then 
            lv_inst_filter := '/* inst_filter */ s.inst_id=USERENV(''Instance'')';
        when regexp_instr('&ssid_begin','@\*') > 0 or '&ssid_begin' like '(%' then 
            lv_inst_filter := '/* inst_filter */ 1=1';
        when regexp_instr('&ssid_begin','@\d+')        > 0 then 
            lv_inst_filter := 's.inst_id = ' || regexp_replace('&ssid_begin', '^(.+)@(\d+)(.*)', '\2');
        else
            lv_inst_filter := 's.inst_id=USERENV(''Instance'')';
        --when regexp_instr('&ssid_begin','@\d+')   > 0 then regexp_replace(snapper_sid, '^(.+)@\d+', '\1') || ' AND inst_id = ' || regexp_replace(snapper_sid, '^(.+)@(\d+)(.*)', '\2') 
    end case;

    -- compute sid_filter
    case
        when trim(lower('&ssid_begin')) like 'con_id=%'    then lv_sid_filter   := 's.con_id in ('||get_filter('&ssid_begin')||')';
        when trim(lower('&ssid_begin')) like 'sid=%'       then lv_sid_filter   := 's.sid in ('   ||get_filter('&ssid_begin')||')'; 
        when trim(lower('&ssid_begin')) like 'audsid=%'    then lv_sid_filter   := 's.audsid in ('||get_filter('&ssid_begin')||')'; 
        when trim(lower('&ssid_begin')) like 'user=%'      then lv_sid_filter   := 'lower(username) like '''         ||get_filter('&ssid_begin')||'''';
        when trim(lower('&ssid_begin')) like 'username=%'  then lv_sid_filter   := 'lower(username) like '''         ||get_filter('&ssid_begin')||'''';
        when trim(lower('&ssid_begin')) like 'machine=%'   then lv_sid_filter   := 'lower(machine) like '''          ||get_filter('&ssid_begin')||'''';
        when trim(lower('&ssid_begin')) like 'program=%'   then lv_sid_filter   := 'lower(program) like '''          ||get_filter('&ssid_begin')||'''';
        when trim(lower('&ssid_begin')) like 'service=%'   then lv_sid_filter   := 'lower(service_name) like '''     ||get_filter('&ssid_begin')||'''';
        when trim(lower('&ssid_begin')) like 'module=%'    then lv_sid_filter   := 'lower(module) like '''           ||get_filter('&ssid_begin')||'''';
        when trim(lower('&ssid_begin')) like 'action=%'    then lv_sid_filter   := 'lower(action) like '''           ||get_filter('&ssid_begin')||'''';
        when trim(lower('&ssid_begin')) like 'osuser=%'    then lv_sid_filter   := 'lower(osuser) like '''           ||get_filter('&ssid_begin')||'''';
        when trim(lower('&ssid_begin')) like 'client_id=%' then lv_sid_filter   := 'lower(client_identifier) like '''||get_filter('&ssid_begin')||'''';
        when trim(lower('&ssid_begin')) like 'spid=%'      then lv_sid_filter   := '(s.inst_id,s.paddr) in (select /*+ UNNEST */ inst_id,addr from gv$process where spid in ('||get_filter('&ssid_begin')||'))';
        when trim(lower('&ssid_begin')) like 'ospid=%'     then lv_sid_filter   := '(s.inst_id,s.paddr) in (select /*+ UNNEST */ inst_id,addr from gv$process where spid in ('||get_filter('&ssid_begin')||'))';
        when trim(lower('&ssid_begin')) like 'pid=%'       then lv_sid_filter   := '(s.inst_id,s.paddr) in (select /*+ UNNEST */ inst_id,addr from gv$process where spid in ('||get_filter('&ssid_begin')||'))';
        when trim(lower('&ssid_begin')) like 'qcsid=%'     then lv_sid_filter   := '(s.inst_id,s.sid)   in (select /*+ NO_UNNEST */ inst_id,sid from gv$px_session where qcsid in ('||get_filter('&ssid_begin')||'))';
        when trim(lower('&ssid_begin')) like 'qc=%'        then lv_sid_filter   := '(s.inst_id,s.sid)   in (select /*+ NO_UNNEST */ inst_id,sid from gv$px_session where qcsid in ('||get_filter('&ssid_begin')||'))';
        when trim(lower('&ssid_begin')) like 'all%'        then lv_sid_filter   := '1=1';
        when trim(lower('&ssid_begin')) like 'bg%'         then lv_sid_filter   := 'type=''BACKGROUND''';
        when trim(lower('&ssid_begin')) like 'fg%'         then lv_sid_filter   := 'type=''USER''';
        when trim(lower('&ssid_begin')) like 'smon%'       then lv_sid_filter   := 'program like ''%(SMON)%''';
        when trim(lower('&ssid_begin')) like 'pmon%'       then lv_sid_filter   := 'program like ''%(PMON)%''';
        when trim(lower('&ssid_begin')) like 'ckpt%'       then lv_sid_filter   := 'program like ''%(CKPT)%''';
        when trim(lower('&ssid_begin')) like 'lgwr%'       then lv_sid_filter   := 'program like ''%(LG__)%'''; -- 12c multiple adaptive LGWR workers
        when trim(lower('&ssid_begin')) like 'dbwr%'       then lv_sid_filter   := 'regexp_like(program, ''.*\((DBW.|BW..)\).*'', ''i'')';
        when trim(lower('&ssid_begin')) like 'select%'     then lv_sid_filter   := q'{(s.inst_id,s.sid) in (&snapper_sid)}';
        when trim(lower('&ssid_begin')) like '(%'          then lv_inst_filter  := '/* inst_filter2 */ 1=1'; lv_sid_filter := q'{(s.inst_id,s.sid) in (&snapper_sid)}'; 
        else                                                    lv_sid_filter   := '/* sid_filter_else_cond */ s.sid in ('||get_filter('&ssid_begin')||')'; 
    end case;

    :inst_filter := lv_inst_filter;
    :sid_filter  := lv_inst_filter||' and '||lv_sid_filter;

    -- this block determines whether dbms_system.ksdwrt is accessible to us
    -- dbms_describe is required as all_procedures/all_objects may show this object
    -- even if its not executable by us (thanks to o7_dictionary_accessibility=false)
    begin
        execute immediate 'select count(*) from x$kcbwh where rownum = 1' into tmp;
        :x:= ' '; -- x$ tables are accessible, so dont comment any lines out
    exception
        when others then null;
    end;

    sys.dbms_describe.describe_procedure(
        'DBMS_SYSTEM.KSDWRT', null, null,
        o, p, l, a, dty, def, inout, len, prec, scal, rad, spa
    );

    -- we never get to following statement if dbms_system is not accessible
    -- as sys.dbms_describe will raise an exception
    :v:= '-- dbms_system is accessible';

exception
    when others then null;
end;
/

-- this query populates some sqlplus variables required for dynamic compilation used below
with mod_banner as (
    select
        replace(banner,'9.','09.') banner
    from
        v$version
    where rownum = 1
)
select
    case when substr(banner, instr(banner, 'Release ')+8,2) >= '12' then '' else '--' end snapper_ora12higher,
    case when substr(banner, instr(banner, 'Release ')+8,2)  < '12' then '' else '--' end snapper_ora12lower,
    case when substr(banner, instr(banner, 'Release ')+8,2)  = '11' then '' else '--' end snapper_ora11higher,
    case when substr(banner, instr(banner, 'Release ')+8,2)  < '11' then '' else '--' end snapper_ora11lower,
    nvl(:v, '/* dbms_system is not accessible') dbms_system_accessible,
    nvl(:x, '--') x_accessible,
    case when substr( banner, instr(banner, 'Release ')+8, instr(substr(banner,instr(banner,'Release ')+8),' ') ) >= '10.2'     then ''   else '--' end yes_blk_inst,
    case when substr( banner, instr(banner, 'Release ')+8, instr(substr(banner,instr(banner,'Release ')+8),' ') ) >= '10.2'     then '--' else ''   end no_blk_inst,
    case when substr( banner, instr(banner, 'Release ')+8, instr(substr(banner,instr(banner,'Release ')+8),' ') ) >= '10.2.0.3' then ''   else '--' end yes_plsql_obj_id,
    case when substr( banner, instr(banner, 'Release ')+8, instr(substr(banner,instr(banner,'Release ')+8),' ') ) >= '10.2.0.3' then '--' else ''   end no_plsql_obj_id,
    case when lower('&snapper_options') like '%,begin%' or lower('&snapper_options') like 'begin%' or lower('&snapper_options') like '%,end%' or lower('&snapper_options') like 'end%' then '' else '--' end manual_snapshot,
    case when lower('&snapper_options') like '%,begin%' or lower('&snapper_options') like 'begin%' or lower('&snapper_options') like '%,end%' or lower('&snapper_options') like 'end%' then '--' else '' end use_dbms_lock,
    :sid_filter  sid_filter,
    :inst_filter inst_filter
from
    mod_banner
/

-- current workaround: 1st serveroutput command below is for sql developer compatibility
-- 2nd is for sqlplus, so that newlines and leading spaces get properly printed
set termout off
set serveroutput on size 1000000 
set serveroutput on size 1000000 format wrapped
set termout on

prompt Sampling SID &4 with interval &snapper_sleep seconds, taking &snapper_count snapshots...

-- let the Snapping start!!!
-- main()
declare
    -- Snapper start
    -- forward declarations
    procedure output(p_txt in varchar2);
    procedure fout;

    function tptformat( p_num in number,
                        p_stype in varchar2 default 'STAT',
                        p_precision in number default 2,
                        p_base in number default 10,
                        p_grouplen in number default 3
                   )
                   return varchar2;
    function getopt( p_parvalues in varchar2,
                     p_extract in varchar2,
                     p_delim in varchar2 default ','
                   )
                   return varchar2;


    -- type, constant, variable declarations

    -- trick for holding 32bit UNSIGNED event and stat_ids in 32bit SIGNED PLS_INTEGER
    pls_adjust constant number(10,0) := power(2,31) - 1;

    type srec is record (ts timestamp, stype varchar2(4), inst_id number, sid number, statistic# number, value number, event_count number );
    type stab is table of srec index by pls_integer;
    type ltab is table of srec index by varchar2(100); -- lookup tab for various average calculation
    s1 stab;
    s2 stab;
    l1 ltab;
    l2 ltab;

    type snrec is record (stype varchar2(4), statistic# number, name varchar2(100));
    type sntab is table of snrec index by pls_integer;
    sn_tmp sntab;
    sn sntab;

    type sntab_reverse is table of snrec index by varchar2(100); -- used for looking up stat id from stat name
    sn_reverse sntab_reverse;

    tmp_varchar2 varchar2(1000); -- misc

    function get_useful_average(c in srec /* curr_metric */, p in srec /* all_prev_metrics */) return varchar2;

    type tmp_sestab is table of gv$session%rowtype index by pls_integer;
    type sestab is table of gv$session%rowtype index by varchar2(20);
        
    g_sessions           sestab;
    g_empty_sessions     sestab;

    type hc_tab is table of number index by pls_integer; -- index is sql hash value
    type ses_hash_tab is table of hc_tab index by pls_integer; -- index is SID
    
    g_ses_hash_tab       ses_hash_tab;
    g_empty_ses_hash_tab ses_hash_tab;

    -- dbms_debug_vc2coll is a built-in collection present in every oracle db
    g_ash                sys.dbms_debug_vc2coll := new sys.dbms_debug_vc2coll();
    g_empty_ash          sys.dbms_debug_vc2coll := new sys.dbms_debug_vc2coll();
    g_snap1              sys.dbms_debug_vc2coll; 
    g_snap2              sys.dbms_debug_vc2coll; 

    g_ash_samples_taken  number := 0;

    g_count_statname  number;
    g_count_eventname number;

    g_mysid           number;

    i number;
    a number;
    b number;

    c number;
    delta number;
    evcnt number;
    changed_values number;
    pagesize number:=99999999999999;
    missing_values_s1 number := 0;
    missing_values_s2 number := 0;
    disappeared_sid   number := 0;
    lv_curr_sid       number := 0; -- used for determining whether to print an empty line between session stats
    d1 timestamp(6);
    d2 timestamp(6);
    ash_date1 date;
    ash_date2 date;
    lv_gather        varchar2(1000);
    gv_header_string varchar2(1000);
    lv_data_string   varchar2(1000);

    lv_ash           varchar2(1000);
    lv_stats         varchar2(1000);

    gather_stats     number := 0;
    gather_ash       number := 0;

    g_snap_begin    varchar2(1000);
    g_snap_end      varchar2(1000);

    -- CONFIGURABLE STUFF --

    -- this sets what are the default ash sample TOP reporting group by columns
    g_ash_columns     varchar2(1000) := 'inst_id + sql_id + sql_child_number + event + wait_class';
    g_ash_columns1    varchar2(1000) := 'inst_id + event + p1 + wait_class';
    g_ash_columns2    varchar2(1000) := 'inst_id + sid + user + machine + program';
    g_ash_columns3    varchar2(1000) := 'inst_id + plsql_object_id + plsql_subprogram_id + sql_id';
    g_ash_columns4    varchar2(1000) := 'con_id + inst_id + sql_id + sql_child_number + event + wait_class';
    g_ash_columns5    varchar2(1000) := 'con_id + inst_id + event + p1 + wait_class';
    g_ash_columns6    varchar2(1000) := 'con_id + inst_id + sid + user + machine + program';
    
    -- output column configuration
    output_header     number := 0; -- 1=true 0=false
    output_username   number := 1; -- v$session.username
    output_inst       number := 0; -- inst
    output_sid        number := CASE WHEN dbms_utility.is_cluster_database = TRUE THEN 0 ELSE 1 END; -- just sid 
    output_inst_sid   number := CASE WHEN dbms_utility.is_cluster_database = TRUE THEN 1 ELSE 0 END; -- inst_id and sid together 
    output_time       number := 0; -- time of snapshot start
    output_seconds    number := 0; -- seconds in snapshot (shown in footer of each snapshot too)
    output_stype      number := 1; -- statistic type (WAIT,STAT,TIME,ENQG,LATG,...)
    output_sname      number := 1; -- statistic name
    output_delta      number := 1; -- raw delta
    output_delta_s    number := 0; -- raw delta normalized to per second
    output_hdelta     number := 0; -- human readable delta
    output_hdelta_s   number := 1; -- human readable delta normalized to per second
    output_percent    number := 1; -- percent of total time/samples
    output_eventcnt   number := 1; -- wait event count
    output_eventcnt_s number := 1; -- wait event count
    output_eventavg   number := 1; -- average wait duration
    output_pcthist    number := 1; -- percent of total visual bar (histogram) -- Histograms seem to work for me on 9.2.0.7 + - JBJ2)

    output_actses     number := 1; -- show Average Active Sessions (AAS) in "ASH" activity section
    output_actses_pct number := 1; -- show AAS as a percentage of a single thread time

    -- column widths in ASH report output
    w_inst_id                     number :=  4;
    w_sid                         number :=  6;
    w_username                    number := 20;
    w_machine                     number := 20;
    w_terminal                    number := 20;
    w_program                     number := 25;
    w_event                       number := 35;
    w_wait_class                  number := 15;
    w_state                       number :=  8;
    w_p1                          number := 20;
    w_p2                          number := 20;
    w_p3                          number := 20;
    w_row_wait_obj#               number := 10;
    w_row_wait_file#              number :=  6;
    w_row_wait_block#             number := 10;
    w_row_wait_row#               number :=  6;
    w_blocking_session_status     number := 15;
    w_blocking_instance           number := 12;
    w_blocking_session            number := 12;
    w_sql_hash_value              number := 12;
    w_sql_id                      number := 15;
    w_sql_child_number            number :=  9;
    w_plsql_entry_object_id       number := 10;
    w_plsql_entry_subprogram_id   number := 10;
    w_plsql_object_id             number := 10;
    w_plsql_subprogram_id         number := 10;
    w_module                      number := 25;
    w_action                      number := 25;
    w_client_identifier           number := 25;
    w_service_name                number := 25;
    w_con_id                      number :=  6;

    w_actses                      number :=  8;
    w_actses_pct                  number := 10;

    -- END CONFIGURABLE STUFF --

    -- constants for ash collection extraction from the vc2 collection
    s_inst_id                      constant number :=  1 ;
    s_sid                          constant number :=  2 ;
    s_username                     constant number :=  3 ;
    s_machine                      constant number :=  4 ;
    s_terminal                     constant number :=  5 ;
    s_program                      constant number :=  6 ;
    s_event                        constant number :=  7 ;
    s_wait_class                   constant number :=  8 ;
    s_state                        constant number :=  9 ;
    s_p1                           constant number := 10 ;
    s_p2                           constant number := 11 ;
    s_p3                           constant number := 12 ;
    s_row_wait_obj#                constant number := 13 ;
    s_row_wait_file#               constant number := 14 ;
    s_row_wait_block#              constant number := 15 ;
    s_row_wait_row#                constant number := 16 ;
    s_blocking_session_status      constant number := 17 ;
    s_blocking_instance            constant number := 18 ;
    s_blocking_session             constant number := 19 ;
    s_sql_hash_value               constant number := 20 ;
    s_sql_id                       constant number := 21 ;
    s_sql_child_number             constant number := 22 ;
    s_plsql_entry_object_id        constant number := 23 ;
    s_plsql_entry_subprogram_id    constant number := 24 ;
    s_plsql_object_id              constant number := 25 ;
    s_plsql_subprogram_id          constant number := 26 ;
    s_module                       constant number := 27 ;
    s_action                       constant number := 28 ;
    s_client_identifier            constant number := 29 ;
    s_service_name                 constant number := 30 ;
    s_con_id                       constant number := 31 ;

    -- constants for ash collection reporting, which columns to show in report
    c_inst_id                      constant number := power(2, s_inst_id                  );
    c_sid                          constant number := power(2, s_sid                      );
    c_username                     constant number := power(2, s_username                 );
    c_machine                      constant number := power(2, s_machine                  );
    c_terminal                     constant number := power(2, s_terminal                 );
    c_program                      constant number := power(2, s_program                  );
    c_event                        constant number := power(2, s_event                    );
    c_wait_class                   constant number := power(2, s_wait_class               );
    c_state                        constant number := power(2, s_state                    );
    c_p1                           constant number := power(2, s_p1                       );
    c_p2                           constant number := power(2, s_p2                       );
    c_p3                           constant number := power(2, s_p3                       );
    c_row_wait_obj#                constant number := power(2, s_row_wait_obj#            );
    c_row_wait_file#               constant number := power(2, s_row_wait_file#           );
    c_row_wait_block#              constant number := power(2, s_row_wait_block#          );
    c_row_wait_row#                constant number := power(2, s_row_wait_row#            );
    c_blocking_session_status      constant number := power(2, s_blocking_session_status  );
    c_blocking_instance            constant number := power(2, s_blocking_instance        );
    c_blocking_session             constant number := power(2, s_blocking_session         );
    c_sql_hash_value               constant number := power(2, s_sql_hash_value           );
    c_sql_id                       constant number := power(2, s_sql_id                   );
    c_sql_child_number             constant number := power(2, s_sql_child_number         );
    c_plsql_entry_object_id        constant number := power(2, s_plsql_entry_object_id    );
    c_plsql_entry_subprogram_id    constant number := power(2, s_plsql_entry_subprogram_id);
    c_plsql_object_id              constant number := power(2, s_plsql_object_id          );
    c_plsql_subprogram_id          constant number := power(2, s_plsql_subprogram_id      );
    c_module                       constant number := power(2, s_module                   );
    c_action                       constant number := power(2, s_action                   );
    c_client_identifier            constant number := power(2, s_client_identifier        );
    c_service_name                 constant number := power(2, s_service_name             );
    c_con_id                       constant number := power(2, s_con_id                   );


  /*---------------------------------------------------
    -- proc for outputting data to trace or dbms_output
    ---------------------------------------------------*/
    procedure output(p_txt in varchar2) is
    begin

        if (getopt('&snapper_options', 'out') is not null)
            or
           (getopt('&snapper_options', 'out') is null and getopt('&snapper_options', 'trace') is null)
        then
            dbms_output.put_line(p_txt);
        end if;

        -- The block below is a sqlplus trick for conditionally commenting out PL/SQL code
        &_IF_DBMS_SYSTEM_ACCESSIBLE
        if getopt('&snapper_options', 'trace') is not null then
            sys.dbms_system.ksdwrt(1, p_txt);
            sys.dbms_system.ksdfls;
        end if;
        -- */
    end; -- output

   /*---------------------------------------------------
   -- function for converting interval datatype to microseconds
   ---------------------------------------------------*/
   function get_seconds(i interval day to second) return number
   as
       s NUMBER;
   begin
       s :=   to_number(extract(second from i)) +
              to_number(extract(minute from i)) * 60 + 
              to_number(extract(hour   from i)) * 60 * 60 + 
              to_number(extract(day    from i)) * 60 * 60 * 24;
       --output('get_seconds '||to_char(i)||' = '||to_char(s)); 
       return s;
   end get_seconds;

  /*---------------------------------------------------
    -- proc for outputting data, utilizing global vars
    ---------------------------------------------------*/
    procedure fout is
        l_output_username VARCHAR2(100);
        gsid varchar2(20);
    begin
        --if s2(b).stype='WAIT' then output( 'DEBUG WAIT ' || sn(s2(b).statistic#).name || ' ' || delta ); end if;
        --output( 'DEBUG, Entering fout(), b='||to_char(b)||' sn(s2(b).statistic#='||s2(b).statistic# );
        --output( 'DEBUG, In fout(), a='||to_char(a)||' b='||to_char(b)||' s1.count='||s1.count||' s2.count='||s2.count||' s2.count='||s2.count);

        gsid := trim(to_char(s2(b).inst_id))||','||trim(to_char(s2(b).sid));

        if output_username = 1 then
            begin
                l_output_username := nvl( g_sessions(gsid).username, substr(g_sessions(gsid).program, instr(g_sessions(gsid).program,'(')) );
            exception
                when no_data_found then l_output_username := 'error';
                when others then raise;
            end;
        end if;

        -- DEBUG
        --output('before');
        --output (CASE WHEN output_eventavg    = 1 THEN CASE WHEN s2(b).stype IN ('WAIT') THEN lpad(tptformat(delta / CASE WHEN evcnt = 0 THEN 1 ELSE evcnt END, s2(b).stype), 10, ' ')||' average wait' ELSE get_useful_average(s2(b), s1(a)) END END);
        --output('after');

        output( CASE WHEN output_header      = 1 THEN 'SID= ' END
             || CASE WHEN output_inst        = 1 THEN to_char(s2(b).inst_id, '9999')||', ' END
             || CASE WHEN output_sid         = 1 THEN to_char(s2(b).sid,'999999')||', ' END
             || CASE WHEN output_inst_sid    = 1 THEN to_char(s2(b).sid,'99999')||' '||lpad('@'||trim(to_char(s2(b).inst_id, '99')),3)||', ' END
             || CASE WHEN output_username    = 1 THEN rpad(CASE s2(b).sid WHEN -1 THEN ' ' ELSE NVL(l_output_username, ' ') END, 10)||', ' END
             || CASE WHEN output_time        = 1 THEN to_char(d1, 'YYYYMMDD HH24:MI:SS')||', ' END
             || CASE WHEN output_seconds     = 1 THEN to_char(case get_seconds(d2-d1) when 0 then &snapper_sleep else get_seconds(d2-d1) end, '9999999')||', ' END
             || CASE WHEN output_stype       = 1 THEN s2(b).stype||', ' END
             || CASE WHEN output_sname       = 1 THEN rpad(sn(s2(b).statistic#).name, 58, ' ')||', ' END
             || CASE WHEN output_delta       = 1 THEN to_char(delta, '999999999999')||', ' END
             || CASE WHEN output_delta_s     = 1 THEN to_char(delta/(case get_seconds(d2-d1) when 0 then &snapper_sleep else get_seconds(d2-d1) end),'999999999')||', ' END
             || CASE WHEN output_hdelta      = 1 THEN lpad(tptformat(delta, s2(b).stype), 10, ' ')||', ' END
             || CASE WHEN output_hdelta_s    = 1 THEN lpad(tptformat(delta/(case get_seconds(d2-d1) when 0 then &snapper_sleep else get_seconds(d2-d1) end ), s2(b).stype), 10, ' ')||', ' END
             || CASE WHEN output_percent     = 1 THEN CASE WHEN s2(b).stype IN ('TIME','WAIT') THEN to_char(delta/CASE get_seconds(d2-d1) WHEN 0 THEN &snapper_sleep ELSE get_seconds(d2-d1) END / 10000, '9999.9')||'%' ELSE '        ' END END||', '
             || CASE WHEN output_pcthist     = 1 THEN CASE WHEN s2(b).stype IN ('TIME','WAIT') THEN rpad(rpad('[', ceil(round(delta/CASE get_seconds(d2-d1) WHEN 0 THEN &snapper_sleep ELSE get_seconds(d2-d1) END / 100000,1))+1, CASE WHEN s2(b).stype IN ('WAIT') THEN 'W' WHEN sn(s2(b).statistic#).name = 'DB CPU' THEN '@' ELSE '#' END),11,' ')||']' ELSE '            ' END END||', '
             || CASE WHEN output_eventcnt    = 1 THEN CASE WHEN s2(b).stype IN ('WAIT') THEN to_char(evcnt, '99999999') ELSE '         ' END END||', '
             || CASE WHEN output_eventcnt_s  = 1 THEN CASE WHEN s2(b).stype IN ('WAIT') THEN lpad(tptformat((evcnt / case get_seconds(d2-d1) when 0 then &snapper_sleep else get_seconds(d2-d1) end ), 'STAT' ), 10, ' ') ELSE '          ' END END||', '
             || CASE WHEN output_eventavg    = 1 THEN CASE WHEN s2(b).stype IN ('WAIT') THEN lpad(tptformat(delta / CASE WHEN evcnt = 0 THEN 1 ELSE evcnt END, s2(b).stype), 10, ' ')||' average wait' ELSE get_useful_average(s2(b), s1(a)) END END
        );

    end;

  
  /*---------------------------------------------------
   -- lookup stat delta helper calculator (l2.value - l1.value)
   ---------------------------------------------------*/
    function get_delta(metric_id in varchar2) return number
    is
        rec1 srec;
        rec2 srec;

        val1 number;
        val2 number;

        d    number;
    begin
        begin 
            val1 := l1(metric_id).value;
        exception
            when no_data_found then val1 := 0;
        end;

        begin
            val2 := l2(metric_id).value;
        exception
            when no_data_found then val2 := 0;
        end;

        d := val2 - NVL(val1, 0);
        return d;
    end get_delta;

  /*---------------------------------------------------
   -- delta helper function for convenience - it allows to specify any metric delta, if not specified then get current one
   ---------------------------------------------------*/
    function gd(c in srec, metric_type in varchar2 DEFAULT NULL, metric_name in varchar2 DEFAULT NULL) return number
    is
        str varchar2(1000);
        tmp_delta number;
    begin
        if metric_type || metric_name  is null then
            str := c.stype||','||trim(to_char(c.inst_id))||','||trim(to_char(c.sid))||','||trim(to_char(c.statistic#,'999999999999999999999999'));
        else 
            begin
                str := trim(metric_type)||','||trim(to_char(c.inst_id))||','||trim(to_char(c.sid))||','||trim(to_char(sn_reverse(metric_type||','||metric_name).statistic#));
            exception
                when no_data_found then return 0;
            end;
        end if;
        tmp_delta := get_delta(str);
        --output('tmp_delta '||c.stype||' '||tmp_delta);
        return tmp_delta;
        -- return get_delta(str);
    end; 

    /*---------------------------------------------------
     -- function for calculating useful averages and ratios between metrics
     -- it is totally OK to show ratios together with raw values they have been derived from
     ---------------------------------------------------*/
    function get_useful_average(c in srec /* curr_metric */, p in srec /* all_prev_metrics */) return varchar2
    is
        ret varchar2(1000);
        mt  varchar2(100) := c.stype; -- metric_type
        mn  varchar2(100) := sn(c.statistic#).name; -- metric_name
    begin
        case 
          when mt = 'STAT' then
            case 
              when mn LIKE 'session _ga memory%'                   then ret := lpad( tptformat(gd(c), 'STAT'), 10) || ' actual value in end of snapshot';
              when mn LIKE '%ed%cursors current'                   then ret := lpad( tptformat(gd(c), 'STAT'), 10) || ' actual value in end of snapshot';
              when mn = 'file io service time'                     then ret := lpad( tptformat(gd(c) / nullif(gd(c, 'STAT', 'physical read total IO requests')+gd(c, 'STAT', 'physical write total IO requests'),0), 'TIME'), 10) || ' bad guess of IO service time per IO request';
              when mn = 'file io wait time'                        then ret := lpad( tptformat(gd(c) / nullif(gd(c, 'STAT', 'physical read total IO requests')+gd(c, 'STAT', 'physical write total IO requests'),0), 'TIME'), 10) || ' bad guess of IO wait time per IO request';
              when mn = 'redo synch time overhead (usec)'          then ret := lpad( tptformat(gd(c) / nullif(gd(c, 'STAT', 'redo synch writes'            ),0), 'TIME'), 10) || ' FG wakeup overhead per log file sync';
              when mn = 'redo write time'                          then ret := lpad( tptformat(gd(c) * 10000 / nullif(gd(c, 'STAT', 'redo writes'          ),0), 'TIME'), 10) || ' per redo write';
              when mn = 'recursive calls'                          then ret := lpad( tptformat(gd(c, 'STAT', 'recursive cpu usage') * 10000 / nullif(gd(c),  0), 'TIME'), 10) || ' recursive CPU per recursive call';
              when mn = 'recursive cpu usage'                      then ret := lpad( tptformat(gd(c) * 10000, 'TIME'), 10) || ' total recursive CPU usage';
              when mn = 'parse time cpu'                           then ret := lpad( tptformat(gd(c) * 10000, 'TIME'), 10) || ' total parse time CPU';
              when mn = 'parse time elapsed'                       then ret := lpad( tptformat(gd(c) * 10000, 'TIME'), 10) || ' total parse time elapsed';
              when mn = 'CPU used when call started'               then ret := lpad( tptformat(gd(c) * 10000, 'TIME'), 10) || ' total CPU used when call started';
              when mn = 'CPU used by this session'                 then ret := lpad( tptformat(gd(c) * 10000, 'TIME'), 10) || ' total CPU used by this session';
              when mn = 'DB Time'                                  then ret := lpad( tptformat(gd(c) * 10000, 'TIME'), 10) || ' total DB Time';
              when mn = 'physical write IO requests'               then ret := lpad( tptformat(gd(c, 'STAT', 'physical write bytes')       / nullif(gd(c),0), mt), 10) || ' bytes per request' ;
              when mn = 'physical write total IO requests'         then ret := lpad( tptformat(gd(c, 'STAT', 'physical write total bytes') / nullif(gd(c),0), mt), 10) || ' bytes per request' ;
              when mn = 'physical write total multi block requests' then ret:= lpad( tptformat(gd(c, 'STAT', 'physical write total IO requests') - gd(c), mt), 10) || ' total single block write requests' ;
              when mn = 'physical read total multi block requests' then ret := lpad( tptformat(gd(c, 'STAT', 'physical read total IO requests') - gd(c), mt), 10) || ' total single block read requests' ;
              when mn = 'physical read IO requests'                then ret := lpad( tptformat(gd(c, 'STAT', 'physical read bytes' )       / nullif(gd(c),0), mt), 10) || ' bytes per request' ;
              when mn = 'physical read read IO requests'           then ret := lpad( tptformat(gd(c, 'STAT', 'physical read total bytes' ) / nullif(gd(c),0), mt), 10) || ' bytes per request' ;
              when mn = 'bytes sent via SQL*Net to client'         then ret := lpad( tptformat(gd(c) / nullif(gd(c, 'STAT', 'SQL*Net roundtrips to/from client'),0), mt), 10) || ' bytes per roundtrip' ;
              when mn = 'bytes received via SQL*Net from client'   then ret := lpad( tptformat(gd(c) / nullif(gd(c, 'STAT', 'SQL*Net roundtrips to/from client'),0), mt), 10) || ' bytes per roundtrip' ;
              when mn = 'bytes sent via SQL*Net to dblink'         then ret := lpad( tptformat(gd(c) / nullif(gd(c, 'STAT', 'SQL*Net roundtrips to/from dblink'),0), mt), 10) || ' bytes per roundtrip' ;
              when mn = 'bytes received via SQL*Net from dblink'   then ret := lpad( tptformat(gd(c) / nullif(gd(c, 'STAT', 'SQL*Net roundtrips to/from dblink'),0), mt), 10) || ' bytes per roundtrip' ;
              when mn = 'redo size'                                then ret := lpad( tptformat(gd(c) / nullif(gd(c, 'STAT', 'user commits'                     ),0), mt), 10) || ' bytes per user commit';
              when mn = 'execute count'                            then ret := lpad( tptformat(gd(c) / nullif(gd(c, 'STAT', 'parse count (total)'              ),0), mt), 10) || ' executions per parse';
              when mn = 'parse count (total)'                      then ret := lpad( tptformat(gd(c) / nullif(gd(c, 'STAT', 'parse count (hard)'               ),0), mt), 10) || ' softparses per hardparse';
              when mn = 'session cursor cache hits'                then ret := lpad( tptformat(gd(c) -       (gd(c, 'STAT', 'parse count (total)'              )  ), mt), 10) || ' softparses avoided thanks to cursor cache';
              when mn = 'session logical reads'                    then ret := lpad( tptformat(gd(c) +       (gd(c, 'STAT', 'buffer is pinned count'           )  ), mt), 10) || ' total buffer visits';
              when mn = 'buffer is pinned count'                   then ret := lpad( tptformat(gd(c) / nullif(gd(c) + gd(c, 'STAT', 'session logical reads'),0) * 100, mt), 10) || ' % buffer gets avoided thanks to buffer pin caching';
              else ret :=                                                      lpad( tptformat(gd(c) / nullif(gd(c, 'STAT', 'execute count'),0), mt), 10) || ' per execution' ;
            end case; -- mt=stat, mn
          when mt = 'TIME' then
            -- this is ugly and wrong at the moment - will refactor some day
            case
              when mn = 'DB time' or mn= 'background elapsed time' then ret := lpad(tptformat((get_seconds(d2 - d1)*1000000 - (
                                                                                                              gd(c) 
                                                                                                            /*+ gd(c, 'DB CPU', 'TIME') */
                                                                                                              + gd(c, 'WAIT', 'pmon timer')
                                                                                                              + gd(c, 'WAIT', 'VKTM Logical Idle Wait')
                                                                                                              + gd(c, 'WAIT', 'VKTM Init Wait for GSGA')
                                                                                                              + gd(c, 'WAIT', 'IORM Scheduler Slave Idle Wait')
                                                                                                              + gd(c, 'WAIT', 'rdbms ipc message')
                                                                                                              + gd(c, 'WAIT', 'OFS idle')
                                                                                                              + gd(c, 'WAIT', 'i/o slave wait')
                                                                                                              + gd(c, 'WAIT', 'VKRM Idle')
                                                                                                              + gd(c, 'WAIT', 'wait for unread message on broadcast channel')
                                                                                                              + gd(c, 'WAIT', 'wait for unread message on multiple broadcast channels')
                                                                                                              + gd(c, 'WAIT', 'class slave wait')
                                                                                                              + gd(c, 'WAIT', 'PING')
                                                                                                              + gd(c, 'WAIT', 'watchdog main loop')
                                                                                                              + gd(c, 'WAIT', 'process in prespawned state')
                                                                                                              + gd(c, 'WAIT', 'DIAG idle wait')
                                                                                                              + gd(c, 'WAIT', 'ges remote message')
                                                                                                              + gd(c, 'WAIT', 'gcs remote message')
                                                                                                              + gd(c, 'WAIT', 'heartbeat monitor sleep')
                                                                                                              + gd(c, 'WAIT', 'GCR sleep')
                                                                                                              + gd(c, 'WAIT', 'SGA: MMAN sleep for component shrink')
                                                                                                              + gd(c, 'WAIT', 'MRP redo arrival')
                                                                                                              + gd(c, 'WAIT', 'LNS ASYNC archive log')
                                                                                                              + gd(c, 'WAIT', 'LNS ASYNC dest activation')
                                                                                                              + gd(c, 'WAIT', 'LNS ASYNC end of log')
                                                                                                              + gd(c, 'WAIT', 'simulated log write delay')
                                                                                                              + gd(c, 'WAIT', 'heartbeat redo informer')
                                                                                                              + gd(c, 'WAIT', 'LGWR real time apply sync')
                                                                                                              + gd(c, 'WAIT', 'LGWR worker group idle')
                                                                                                              + gd(c, 'WAIT', 'parallel recovery slave idle wait')
                                                                                                              + gd(c, 'WAIT', 'Backup Appliance waiting for work')
                                                                                                              + gd(c, 'WAIT', 'Backup Appliance waiting restore start')
                                                                                                              + gd(c, 'WAIT', 'Backup Appliance Surrogate wait')
                                                                                                              + gd(c, 'WAIT', 'Backup Appliance Servlet wait')
                                                                                                              + gd(c, 'WAIT', 'Backup Appliance Comm SGA setup wait')
                                                                                                              + gd(c, 'WAIT', 'LogMiner builder: idle')
                                                                                                              + gd(c, 'WAIT', 'LogMiner builder: branch')
                                                                                                              + gd(c, 'WAIT', 'LogMiner preparer: idle')
                                                                                                              + gd(c, 'WAIT', 'LogMiner reader: log (idle)')
                                                                                                              + gd(c, 'WAIT', 'LogMiner reader: redo (idle)')
                                                                                                              + gd(c, 'WAIT', 'LogMiner client: transaction')
                                                                                                              + gd(c, 'WAIT', 'LogMiner: other')
                                                                                                              + gd(c, 'WAIT', 'LogMiner: activate')
                                                                                                              + gd(c, 'WAIT', 'LogMiner: reset')
                                                                                                              + gd(c, 'WAIT', 'LogMiner: find session')
                                                                                                              + gd(c, 'WAIT', 'LogMiner: internal')
                                                                                                              + gd(c, 'WAIT', 'Logical Standby Apply Delay')
                                                                                                              + gd(c, 'WAIT', 'parallel recovery coordinator waits for slave cleanup')
                                                                                                              + gd(c, 'WAIT', 'parallel recovery coordinator idle wait')
                                                                                                              + gd(c, 'WAIT', 'parallel recovery control message reply')
                                                                                                              + gd(c, 'WAIT', 'parallel recovery slave next change')
                                                                                                              + gd(c, 'WAIT', 'recovery sender idle wait')
                                                                                                              + gd(c, 'WAIT', 'recovery receiver idle wait')
                                                                                                              + gd(c, 'WAIT', 'recovery merger idle wait ')
                                                                                                              + gd(c, 'WAIT', 'PX Deq: Txn Recovery Start')
                                                                                                              + gd(c, 'WAIT', 'PX Deq: Txn Recovery Reply')
                                                                                                              + gd(c, 'WAIT', 'fbar timer')
                                                                                                              + gd(c, 'WAIT', 'smon timer')
                                                                                                              + gd(c, 'WAIT', 'PX Deq: Metadata Update')
                                                                                                              + gd(c, 'WAIT', 'Space Manager: slave idle wait')
                                                                                                              + gd(c, 'WAIT', 'PX Deq: Index Merge Reply')
                                                                                                              + gd(c, 'WAIT', 'PX Deq: Index Merge Execute')
                                                                                                              + gd(c, 'WAIT', 'PX Deq: Index Merge Close')
                                                                                                              + gd(c, 'WAIT', 'PX Deq: kdcph_mai')
                                                                                                              + gd(c, 'WAIT', 'PX Deq: kdcphc_ack')
                                                                                                              + gd(c, 'WAIT', 'imco timer')
                                                                                                              + gd(c, 'WAIT', 'virtual circuit next request')
                                                                                                              + gd(c, 'WAIT', 'shared server idle wait')
                                                                                                              + gd(c, 'WAIT', 'dispatcher timer')
                                                                                                              + gd(c, 'WAIT', 'cmon timer')
                                                                                                              + gd(c, 'WAIT', 'pool server timer')
                                                                                                              + gd(c, 'WAIT', 'lreg timer')
                                                                                                              + gd(c, 'WAIT', 'JOX Jit Process Sleep')
                                                                                                              + gd(c, 'WAIT', 'jobq slave wait')
                                                                                                              + gd(c, 'WAIT', 'pipe get')
                                                                                                              + gd(c, 'WAIT', 'PX Deque wait')
                                                                                                              + gd(c, 'WAIT', 'PX Idle Wait')
                                                                                                              + gd(c, 'WAIT', 'PX Deq: Join ACK')
                                                                                                              + gd(c, 'WAIT', 'PX Deq Credit: need buffer')
                                                                                                              + gd(c, 'WAIT', 'PX Deq Credit: send blkd')
                                                                                                              + gd(c, 'WAIT', 'PX Deq: Msg Fragment')
                                                                                                              + gd(c, 'WAIT', 'PX Deq: Parse Reply')
                                                                                                              + gd(c, 'WAIT', 'PX Deq: Execute Reply')
                                                                                                              + gd(c, 'WAIT', 'PX Deq: Execution Msg')
                                                                                                              + gd(c, 'WAIT', 'PX Deq: Table Q Normal')
                                                                                                              + gd(c, 'WAIT', 'PX Deq: Table Q Sample')
                                                                                                              + gd(c, 'WAIT', 'REPL Apply: txns')
                                                                                                              + gd(c, 'WAIT', 'REPL Capture/Apply: messages')
                                                                                                              + gd(c, 'WAIT', 'REPL Capture: archive log')
                                                                                                              + gd(c, 'WAIT', 'single-task message')
                                                                                                              + gd(c, 'WAIT', 'SQL*Net message from client')
                                                                                                              + gd(c, 'WAIT', 'SQL*Net vector message from client')
                                                                                                              + gd(c, 'WAIT', 'SQL*Net vector message from dblink')
                                                                                                              + gd(c, 'WAIT', 'PL/SQL lock timer')
                                                                                                              + gd(c, 'WAIT', 'Streams AQ: emn coordinator idle wait')
                                                                                                              + gd(c, 'WAIT', 'EMON slave idle wait')
                                                                                                              + gd(c, 'WAIT', 'Emon coordinator main loop')
                                                                                                              + gd(c, 'WAIT', 'Emon slave main loop')
                                                                                                              + gd(c, 'WAIT', 'Streams AQ: waiting for messages in the queue')
                                                                                                              + gd(c, 'WAIT', 'Streams AQ: waiting for time management or cleanup tasks')
                                                                                                              + gd(c, 'WAIT', 'Streams AQ: delete acknowledged messages')
                                                                                                              + gd(c, 'WAIT', 'Streams AQ: deallocate messages from Streams Pool')
                                                                                                              + gd(c, 'WAIT', 'Streams AQ: qmn coordinator idle wait')
                                                                                                              + gd(c, 'WAIT', 'Streams AQ: qmn slave idle wait')
                                                                                                              + gd(c, 'WAIT', 'AQ: 12c message cache init wait')
                                                                                                              + gd(c, 'WAIT', 'AQ Cross Master idle')
                                                                                                              + gd(c, 'WAIT', 'AQPC idle')
                                                                                                              + gd(c, 'WAIT', 'Streams AQ: load balancer idle')
                                                                                                              + gd(c, 'WAIT', 'Sharded  Queues : Part Maintenance idle')
                                                                                                              + gd(c, 'WAIT', 'REPL Capture/Apply: RAC AQ qmn coordinator')
                                                                                                              + gd(c, 'WAIT', 'HS message to agent')
                                                                                                              + gd(c, 'WAIT', 'ASM background timer')
                                                                                                              + gd(c, 'WAIT', 'iowp msg')
                                                                                                              + gd(c, 'WAIT', 'iowp file id')
                                                                                                              + gd(c, 'WAIT', 'netp network')
                                                                                                              + gd(c, 'WAIT', 'gopp msg')
                                                                                                              + gd(c, 'WAIT', 'auto-sqltune: wait graph update')
                                                                                                              + gd(c, 'WAIT', 'WCR: replay client notify')
                                                                                                              + gd(c, 'WAIT', 'WCR: replay clock')
                                                                                                              + gd(c, 'WAIT', 'WCR: replay paused')
                                                                                                              + gd(c, 'WAIT', 'JS external job')
                                                                                                              + gd(c, 'WAIT', 'cell worker idle')
                                                                                                          )) / (get_seconds(d2 - d1)*1000000) * 100
                                                                                           , 'STAT'), 10) || ' % unaccounted time' ;
              else null;
            end case; -- mt=time, mn
        else null;
    end case; -- mt
        return ret;
    end get_useful_average;
 
  /*---------------------------------------------------
    -- function for converting large numbers to human-readable format
    ---------------------------------------------------*/
    function tptformat( p_num in number,
                        p_stype in varchar2 default 'STAT',
                        p_precision in number default 2,
                        p_base in number default 10,    -- for KiB/MiB formatting use
                        p_grouplen in number default 3  -- p_base=2 and p_grouplen=10
                      )
                      return varchar2
    is
    begin
        if p_num = 0 then return '0'; end if;
        if p_num IS NULL then return '~'; end if;

        if p_stype in ('WAIT','TIME') then

            return
                round(
                    p_num / power( p_base , trunc(log(p_base,abs(p_num)))-trunc(mod(log(p_base,abs(p_num)),p_grouplen)) ), p_precision
                )
                || case trunc(log(p_base,abs(p_num)))-trunc(mod(log(p_base,abs(p_num)),p_grouplen))
                       when 0            then 'us'
                       when 1            then 'us'
                       when p_grouplen*1 then 'ms'
                       when p_grouplen*2 then 's'
                       when p_grouplen*3 then 'ks'
                       when p_grouplen*4 then 'Ms'
                       else '*'||p_base||'^'||to_char( trunc(log(p_base,abs(p_num)))-trunc(mod(log(p_base,abs(p_num)),p_grouplen)) )||' us'
                    end;

        else

            return
                round(
                    p_num / power( p_base , trunc(log(p_base,abs(p_num)))-trunc(mod(log(p_base,abs(p_num)),p_grouplen)) ), p_precision
                )
                || case trunc(log(p_base,abs(p_num)))-trunc(mod(log(p_base,abs(p_num)),p_grouplen))
                       when 0            then ''
                       when 1            then ''
                       when p_grouplen*1 then 'k'
                       when p_grouplen*2 then 'M'
                       when p_grouplen*3 then 'G'
                       when p_grouplen*4 then 'T'
                       when p_grouplen*5 then 'P'
                       when p_grouplen*6 then 'E'
                       else '*'||p_base||'^'||to_char( trunc(log(p_base,abs(p_num)))-trunc(mod(log(p_base,abs(p_num)),p_grouplen)) )
                    end;

        end if;

    end; -- tptformat

  /*---------------------------------------------------
    -- simple function for parsing arguments from parameter string
    ---------------------------------------------------*/
    function getopt( p_parvalues in varchar2,
                     p_extract in varchar2,
                     p_delim in varchar2 default ','
                   ) return varchar2
    is
        ret varchar(1000) := NULL;
    begin

      -- dbms_output.put('p_parvalues = ['||p_parvalues||'] ' );
      -- dbms_output.put('p_extract = ['||p_extract||'] ' );

        if lower(p_parvalues) like lower(p_extract)||'%'
        or lower(p_parvalues) like '%'||p_delim||lower(p_extract)||'%' then

            ret :=
                nvl (
                    substr(p_parvalues,
                            instr(p_parvalues, p_extract)+length(p_extract),
                            case
                                instr(
                                    substr(p_parvalues,
                                            instr(p_parvalues, p_extract)+length(p_extract)
                                    )
                                    , p_delim
                                )
                            when 0 then length(p_parvalues)
                            else
                                instr(
                                    substr(p_parvalues,
                                            instr(p_parvalues, p_extract)+length(p_extract)
                                    )
                                    , p_delim
                                ) - 1
                            end
                    )
                    , chr(0) -- in case parameter was specified but with no value
                );

        else
            ret := null; -- no parameter found
        end if;

      -- dbms_output.put_line('ret = ['||replace(ret,chr(0),'\0')||']');

        return ret;

    end; -- getopt

  /*---------------------------------------------------
    -- proc for getting session list with username, osuser, machine etc
    ---------------------------------------------------*/
   procedure get_sessions is
       tmp_sessions tmp_sestab;
   begin

       select /*+ unnest */ /* get_session_list:1 */
           *
       bulk collect into
           tmp_sessions
       from
           gv$session s
       where
           1=1
       and (
           &sid_filter
       ) ;

       g_sessions := g_empty_sessions;

       for i in 1..tmp_sessions.count loop
           g_sessions(tmp_sessions(i).inst_id||','||tmp_sessions(i).sid) := tmp_sessions(i);
       end loop;

   end; -- get_sessions

  /*---------------------------------------------------
    -- function for getting session list with username, osuser, machine etc
    -- this func does not update the g_sessions global array but returns session info as return value
    ---------------------------------------------------*/
   function get_sessions return sestab is
       tmp_sessions tmp_sestab;
       l_return_sessions sestab; 
   begin

       select /*+ unnest */ /* get_session_list:2 */
           *
       bulk collect into
           tmp_sessions
       from
           gv$session s
       where
           1=1
       and (&sid_filter) ;

       for i in 1..tmp_sessions.count loop
           --output('get_sessions i='||i||' sid='||tmp_sessions(i).sid);
           l_return_sessions(tmp_sessions(i).inst_id||','||tmp_sessions(i).sid) := tmp_sessions(i);
       end loop;
       
       return l_return_sessions;

   end; -- get_sessions


    /*---------------------------------------------------
    -- functions for extracting and converting gv$session
    -- records to varchar2
    ---------------------------------------------------*/
   function sitem(p in varchar2) return varchar2 as
   begin
      return '<'||translate(p, '<>', '__')||'>';
   end; -- sitem varchar2

   function sitem(p in number) return varchar2 as
   begin
      return '<'||to_char(p)||'>';
   end; -- sitem number 

   function sitem(p in date) return varchar2 as
   begin
      return '<'||to_char(p, 'YYYY-MM-DD HH24:MI:SS')||'>';
   end; -- sitem date

   function sitem_raw(p in raw) return varchar2 as
   begin
      return '<'||upper(rawtohex(p))||'>';
   end; -- sitem_raw


   /*---------------------------------------------------
   -- proc for resetting the snapper ash array
   ---------------------------------------------------*/
   procedure reset_ash is
   begin
      g_ash_samples_taken := 0;
      -- clear g_ash
      g_ash := new sys.dbms_debug_vc2coll(); 
   end; -- reset_ash


   /*---------------------------------------------------
   -- proc for getting ash style samples from gv$session 
   ---------------------------------------------------*/
   procedure extract_ash is
       ash_i varchar2(30);
       s gv$session%rowtype;
       
   begin
       -- keep track how many times we sampled gv$session so we could calculate averages later on
       g_ash_samples_taken := g_ash_samples_taken + 1;
       --output('g_sessions.count='||g_sessions.count);
       ash_i := g_sessions.first;

       while ash_i is not null loop 

          s := g_sessions(ash_i);
          if -- active, on cpu
              (s.status = 'ACTIVE' and s.state != 'WAITING' and s.sid != g_mysid) 
          or -- active, waiting for non-idle wait
              (s.status = 'ACTIVE' and s.state = 'WAITING' and s.wait_class != 'Idle' and s.sid != g_mysid) 
          then 
             --output('extract_ash: i='||i||' sid='||s.sid||' hv='||s.sql_hash_value||' sqlid='||s.sql_id);
             -- if not actually waiting for anything, clear the past wait event details
             if s.state != 'WAITING' then 
                 s.state:='ON CPU';
                 s.event:='ON CPU';
                 s.wait_class:='ON CPU'; --TODO: What do we need to do for 9i here?
                 s.p1:=NULL;
                 s.p2:=NULL;
                 s.p3:=NULL;
             end if;

             g_ash.extend;

             -- max length 1000 bytes (due to dbms_debug_vc2coll)
             g_ash(g_ash.count) := substr(
                            sitem(s.inst_id)                   --  1
                          ||sitem(s.sid)                       --  2
                          ||sitem(s.username)                  --  3  -- 30 bytes
                          ||sitem(s.machine)                   --  4  -- 64 bytes
                          ||sitem(s.terminal)                  --  5  -- 30 bytes
                          ||sitem(s.program)                   --  6  -- 48 bytes
                          ||sitem(s.event)                     --  7  -- 64 bytes
                          ||sitem(s.wait_class)                --  8  -- 64 bytes, 10g+
                          ||sitem(s.state)                     --  9 
                          ||sitem(s.p1)                        -- 10
                          ||sitem(s.p2)                        -- 11
                          ||sitem(s.p3)                        -- 12
                          ||sitem(s.row_wait_obj#)             -- 13
                          ||sitem(s.row_wait_file#)            -- 14
                          ||sitem(s.row_wait_block#)           -- 15
                          ||sitem(s.row_wait_row#)             -- 16
                          ||sitem(s.blocking_session_status)   -- 17   -- 10g+
           &_NO_BLK_INST  ||sitem('N/A')                       -- 17   -- 10gR2+
          &_YES_BLK_INST  ||sitem(s.blocking_instance)         -- 18   -- 10gR2+
                          ||sitem(s.blocking_session)          -- 19   -- 10g+
                          ||sitem(s.sql_hash_value)            -- 20
                          ||sitem(s.sql_id)                    -- 21   -- 10g+
                          ||sitem(s.sql_child_number)          -- 22   -- 10g+
      &_NO_PLSQL_OBJ_ID   ||sitem('N/A')                       -- 23
      &_NO_PLSQL_OBJ_ID   ||sitem('N/A')                       -- 24
      &_NO_PLSQL_OBJ_ID   ||sitem('N/A')                       -- 25
      &_NO_PLSQL_OBJ_ID   ||sitem('N/A')                       -- 26
     &_YES_PLSQL_OBJ_ID   ||sitem(s.plsql_entry_object_id)     -- 23
     &_YES_PLSQL_OBJ_ID   ||sitem(s.plsql_entry_subprogram_id) -- 24
     &_YES_PLSQL_OBJ_ID   ||sitem(s.plsql_object_id)           -- 25
     &_YES_PLSQL_OBJ_ID   ||sitem(s.plsql_subprogram_id)       -- 26
                          ||sitem(s.module)                    -- 27  -- 48 bytes
                          ||sitem(s.action)                    -- 28  -- 32 bytes
                          ||sitem(s.client_identifier)         -- 29  -- 64 bytes
                          ||sitem(s.service_name)              -- 30  -- 64 bytes, 10g+
     &_IF_ORA12_OR_HIGHER ||sitem(s.con_id)                    -- 31  -- 12c+ 
    &_IF_LOWER_THAN_ORA12 ||sitem('N/A')                       -- 31  
                    , 1, 1000);
             
          end if; -- sample is of an active session
          
          ash_i := g_sessions.next(ash_i);
       
       end loop;

   exception
       when no_data_found then output('error in extract_ash(): no_data_found for item '||i);
   end; -- extract_ash


   /*---------------------------------------------------
    -- proc for querying performance data into collections
    ---------------------------------------------------*/
   procedure snap( p_snapdate out timestamp, p_stats out stab, l_stats out ltab, p_stats_string out sys.dbms_debug_vc2coll) is

        lv_include_stat  varchar2(1000) := nvl( lower(getopt('&snapper_options', 'sinclude=' )), '%');
        lv_include_latch varchar2(1000) := nvl( lower(getopt('&snapper_options', 'linclude=' )), '%');
        lv_include_time  varchar2(1000) := nvl( lower(getopt('&snapper_options', 'tinclude=' )), '%');
        lv_include_wait  varchar2(1000) := nvl( lower(getopt('&snapper_options', 'winclude=' )), '%');

        lstr             varchar2(1000);

   begin

        p_snapdate := systimestamp;

        select /* get_session_stats */ p_snapdate ts, snapper_stats.*
        bulk collect into p_stats
        from (
                                         select 'STAT' stype, s.inst_id, s.sid, ss.statistic# - pls_adjust statistic#, ss.value, null event_count
                                         from gv$session s, gv$sesstat ss
                                         where &sid_filter --(inst_id,sid) in (&snapper_sid)
                                         and s.inst_id = ss.inst_id
                                         and s.sid = ss.sid
                                         and  (lv_gather like '%s%' or lv_gather like '%a%')
                                         and ss.statistic# in (select /*+ no_unnest */ statistic# from v$statname
                                                            where lower(name) like '%'||lv_include_stat||'%'
                                                            or regexp_like (name, lv_include_stat, 'i')
                                                           )
                                         --
                                         union all
                                         select
                                                'WAIT', s.inst_id, s.sid,
                                                en.event# + (select count(*) from v$statname) + 1 - pls_adjust,
                                                nvl(se.time_waited_micro,0) + ( decode(se.event||s.state, s.event||'WAITING', 
                                                                                    CASE WHEN s.seconds_in_wait > 1300000000 THEN 0 ELSE s.seconds_in_wait END -- bug in v$session
                                                                              , 0) * 1000000 ) value, total_waits event_count
                                         from gv$session s, gv$session_event se, v$event_name en
                                         where &sid_filter
                                         and   s.sid = se.sid
                                         and   s.inst_id = se.inst_id
                                         and   se.event = en.name
                                         --and   (se.inst_id, se.sid) in (&snapper_sid)
                                         and   (lv_gather like '%w%' or lv_gather like '%a%')
                                         and   en.event#  in (select event# from v$event_name
                                                            where lower(name) like '%'||lv_include_wait||'%'
                                                            or    regexp_like (name, lv_include_wait, 'i')
                                                           )
                                         --
                                         union all
                                         select 'TIME' stype, s.inst_id, s.sid, st.stat_id - pls_adjust statistic#, st.value, null event_count
                                         from gv$session s, gv$sess_time_model st
                                         where &sid_filter --(inst_id,sid) in (&snapper_sid)
                                         and s.inst_id = st.inst_id
                                         and s.sid = st.sid
                                         and   (lv_gather like '%t%' or lv_gather like '%a%')
                                         and st.stat_id in (select stat_id from gv$sys_time_model
                                                            where lower(stat_name) like '%'||lv_include_time||'%'
                                                            or    regexp_like (stat_name, lv_include_time, 'i')
                                                           )
                                         --
                                         union all
                                         select 'LATG', s.inst_id, -1 sid,
                                               s.latch# +
                                                   (select count(*) from v$statname) +
                                                   (select count(*) from v$event_name) +
                                                   1 - pls_adjust statistic#,
                                               s.gets + s.immediate_gets value, null event_count
                                         from gv$latch s
                                         where &inst_filter
                                         and (lv_gather like '%l%' or lv_gather like '%a%')
                                         and latch# in (select latch# from v$latchname
                                                        where lower(name) like '%'||lv_include_latch||'%'
                                                        or    regexp_like (name, lv_include_latch, 'i')
                                                       )
                                         --
 &_IF_X_ACCESSIBLE &_IF_LOWER_THAN_ORA11 union all
 &_IF_X_ACCESSIBLE &_IF_LOWER_THAN_ORA11 select 'BUFG', to_number(sys_context('userenv', 'instance')), -1 sid,
 &_IF_X_ACCESSIBLE &_IF_LOWER_THAN_ORA11       s.indx +
 &_IF_X_ACCESSIBLE &_IF_LOWER_THAN_ORA11           (select count(*) from v$statname) +
 &_IF_X_ACCESSIBLE &_IF_LOWER_THAN_ORA11           (select count(*) from v$event_name) +
 &_IF_X_ACCESSIBLE &_IF_LOWER_THAN_ORA11           (select count(*) from gv$latch) +
 &_IF_X_ACCESSIBLE &_IF_LOWER_THAN_ORA11           1 - pls_adjust statistic#,
 &_IF_X_ACCESSIBLE &_IF_LOWER_THAN_ORA11       s.why0+s.why1+s.why2 value, null event_count
 &_IF_X_ACCESSIBLE &_IF_LOWER_THAN_ORA11 from x$kcbsw s, x$kcbwh w
 &_IF_X_ACCESSIBLE &_IF_LOWER_THAN_ORA11 where
 &_IF_X_ACCESSIBLE &_IF_LOWER_THAN_ORA11       s.indx = w.indx 
 &_IF_X_ACCESSIBLE &_IF_LOWER_THAN_ORA11 and   s.why0+s.why1+s.why2 > 0
 &_IF_X_ACCESSIBLE &_IF_LOWER_THAN_ORA11 and   (lv_gather like '%b%' or lv_gather like '%a%')
                                         --
 &_IF_X_ACCESSIBLE &_IF_ORA11_OR_HIGHER  union all
 &_IF_X_ACCESSIBLE &_IF_ORA11_OR_HIGHER  select 'BUFG', to_number(sys_context('userenv', 'instance')), -1 sid,
 &_IF_X_ACCESSIBLE &_IF_ORA11_OR_HIGHER        sw.indx +
 &_IF_X_ACCESSIBLE &_IF_ORA11_OR_HIGHER            (select count(*) from v$statname) +
 &_IF_X_ACCESSIBLE &_IF_ORA11_OR_HIGHER            (select count(*) from v$event_name) +
 &_IF_X_ACCESSIBLE &_IF_ORA11_OR_HIGHER            (select count(*) from gv$latch) +
 &_IF_X_ACCESSIBLE &_IF_ORA11_OR_HIGHER            1 - pls_adjust statistic#,
 &_IF_X_ACCESSIBLE &_IF_ORA11_OR_HIGHER        why.why0+why.why1+why.why2+sw.other_wait value, null event_count
 &_IF_X_ACCESSIBLE &_IF_ORA11_OR_HIGHER  from
 &_IF_X_ACCESSIBLE &_IF_ORA11_OR_HIGHER        x$kcbuwhy why,
 &_IF_X_ACCESSIBLE &_IF_ORA11_OR_HIGHER        x$kcbwh       dsc,
 &_IF_X_ACCESSIBLE &_IF_ORA11_OR_HIGHER        x$kcbsw       sw
 &_IF_X_ACCESSIBLE &_IF_ORA11_OR_HIGHER  where
 &_IF_X_ACCESSIBLE &_IF_ORA11_OR_HIGHER        why.indx = dsc.indx
 &_IF_X_ACCESSIBLE &_IF_ORA11_OR_HIGHER  and   why.inst_id = dsc.inst_id
 &_IF_X_ACCESSIBLE &_IF_ORA11_OR_HIGHER  and   dsc.inst_id = sw.inst_id
 &_IF_X_ACCESSIBLE &_IF_ORA11_OR_HIGHER  and   why.inst_id = sw.inst_id
 &_IF_X_ACCESSIBLE &_IF_ORA11_OR_HIGHER  and   why.why0 + why.why1 + why.why2 + sw.other_wait > 0
 &_IF_X_ACCESSIBLE &_IF_ORA11_OR_HIGHER  and   dsc.indx = sw.indx
 &_IF_X_ACCESSIBLE &_IF_ORA11_OR_HIGHER  and   why.indx = sw.indx
 &_IF_X_ACCESSIBLE &_IF_ORA11_OR_HIGHER        -- deliberate cartesian join
 &_IF_X_ACCESSIBLE &_IF_ORA11_OR_HIGHER  and   (lv_gather like '%b%' or lv_gather like '%a%')
                                         --
                                         union all
                                         select 'ENQG', s.inst_id, -1 sid,
                                               ascii(substr(s.eq_type,1,1))*256 + ascii(substr(s.eq_type,2,1)) +
                                                   (select count(*) from v$statname) +
                                                   (select count(*) from v$event_name) +
                                                   (select count(*) from gv$latch) +
  &_IF_X_ACCESSIBLE                                (select count(*) from x$kcbwh) +
                                                   1 - pls_adjust statistic#,
                                               s.total_req# value, null event_count
                                         from gv$enqueue_stat s
                                         where &inst_filter
                                         and   (lv_gather like '%e%' or lv_gather like '%a%')
        ) snapper_stats
        order by inst_id, sid, stype, statistic#;

        if p_stats.COUNT > 0 then        
            -- l_stats is an associative array for stats lookup, used for the useful averages calculation
            -- p_stats_string is a dbms_debug_vc2coll collection datatype for "persisting" stats values across snapper DB calls (for "before" and "after" snaps)
            p_stats_string := sys.dbms_debug_vc2coll();
            for s in p_stats.first..p_stats.last loop
                -- type srec is record (stype varchar2(4), sid number, statistic# number, value number, event_count number );
                lstr := p_stats(s).stype||','||trim(to_char(p_stats(s).inst_id))||','||trim(to_char(p_stats(s).sid))||','||trim(to_char(p_stats(s).statistic#,'999999999999999999999999'));
                l_stats(lstr) := p_stats(s);

                if g_snap_begin is not null then
                    p_stats_string.extend();
                    p_stats_string(s) := TO_CHAR(p_stats(s).ts, 'YYYY-MM-DD HH24:MI:SS.FF')              ||','||
                                         p_stats(s).stype                                                ||','||
                                         TO_CHAR(p_stats(s).inst_id)                                     ||','||
                                         TO_CHAR(p_stats(s).sid)                                         ||','||
                                         TRIM(TO_CHAR(p_stats(s).statistic#, '999999999999999999999999'))||','||
                                         TRIM(TO_CHAR(p_stats(s).value,      '999999999999999999999999'))||','||
                                         TRIM(TO_CHAR(p_stats(s).event_count,'999999999999999999999999'));
                    --output('p_stats.p_stats_string='||p_stats_string(s));
                end if;
            end loop; -- s in (p_stats)
        end if;  -- p.stats.COUNT > 0
   end snap;


   /*---------------------------------------------------
    -- proc for reversing the string-normalized
    -- stats array into lookup tables/collections
    ---------------------------------------------------*/
   procedure snap_from_stats_string (p_string_stats in sys.dbms_debug_vc2coll, p_snapdate out timestamp, p_stats out stab, l_stats out ltab)
   is
     lstr varchar2(1000);
     lv_rec srec;
   begin
       p_snapdate := NULL;
       --type srec is record (stype varchar2(4), sid number, statistic# number, value number, event_count number );
       for s in p_string_stats.first .. p_string_stats.last loop
           lv_rec.ts          := TO_TIMESTAMP(replace(regexp_substr(p_string_stats(s)||',', '(.*?),', 1, 1),',',''), 'YYYY-MM-DD HH24:MI:SS.FF');
           lv_rec.stype       :=              replace(regexp_substr(p_string_stats(s)||',', '(.*?),', 1, 2),',','');
           lv_rec.inst_id     :=    TO_NUMBER(replace(regexp_substr(p_string_stats(s)||',', '(.*?),', 1, 3),',',''));
           lv_rec.sid         :=    TO_NUMBER(replace(regexp_substr(p_string_stats(s)||',', '(.*?),', 1, 4),',',''));
           lv_rec.statistic#  :=    TO_NUMBER(replace(regexp_substr(p_string_stats(s)||',', '(.*?),', 1, 5),',',''));
           lv_rec.value       :=    TO_NUMBER(replace(regexp_substr(p_string_stats(s)||',', '(.*?),', 1, 6),',',''));
           lv_rec.event_count :=    TO_NUMBER(replace(regexp_substr(p_string_stats(s)||',', '(.*?),', 1, 7),',',''));
           --output('snap_from_stats_string.event_count = '||to_char(lv_rec.event_count));

           p_stats(s) := lv_rec;
           lstr := p_stats(s).stype||','||trim(to_char(p_stats(s).inst_id))||','||trim(to_char(p_stats(s).sid))||','||trim(to_char(p_stats(s).statistic#,'999999999999999999999999'));
           l_stats(lstr) := p_stats(s);
       end loop;

       p_snapdate := lv_rec.ts;
   end snap_from_stats_string;

   /*---------------------------------------------------
    -- proc for dumping ASH data out in grouped
    -- and ordered fashion
    ---------------------------------------------------*/
    procedure out_ash( p_ash_columns in varchar2, p_topn in number := 10 ) as

        -- whether to print given column or not
        p_inst_id                     number := 0;
        p_sid                         number := 0;
        p_username                    number := 0;
        p_machine                     number := 0;
        p_terminal                    number := 0;
        p_program                     number := 0;
        p_event                       number := 0;
        p_wait_class                  number := 0;
        p_state                       number := 0;
        p_p1                          number := 0;
        p_p2                          number := 0;
        p_p3                          number := 0;
        p_row_wait_obj#               number := 0;
        p_row_wait_file#              number := 0;
        p_row_wait_block#             number := 0;
        p_row_wait_row#               number := 0;
        p_blocking_session_status     number := 0;
        p_blocking_instance           number := 0;
        p_blocking_session            number := 0;
        p_sql_hash_value              number := 0;
        p_sql_id                      number := 0;
        p_sql_child_number            number := 0;
        p_plsql_entry_object_id       number := 0;
        p_plsql_entry_subprogram_id   number := 0;
        p_plsql_object_id             number := 0;
        p_plsql_subprogram_id         number := 0;
        p_module                      number := 0;
        p_action                      number := 0;
        p_client_identifier           number := 0;
        p_service_name                number := 0;
        p_con_id                      number := 0;

        -- temporary variables for holding session details (for later formatting)
        o_inst_id                     varchar2(100);
        o_sid                         varchar2(100);
        o_username                    varchar2(100);
        o_machine                     varchar2(100);
        o_terminal                    varchar2(100);
        o_program                     varchar2(100);
        o_event                       varchar2(100);
        o_wait_class                  varchar2(100);
        o_state                       varchar2(100);
        o_p1                          varchar2(100);
        o_p2                          varchar2(100);
        o_p3                          varchar2(100);
        o_row_wait_obj#               varchar2(100);
        o_row_wait_file#              varchar2(100);
        o_row_wait_block#             varchar2(100);
        o_row_wait_row#               varchar2(100);
        o_blocking_session_status     varchar2(100);
        o_blocking_instance           varchar2(100);
        o_blocking_session            varchar2(100);
        o_sql_hash_value              varchar2(100);
        o_sql_id                      varchar2(100);
        o_sql_child_number            varchar2(100);
        o_plsql_entry_object_id       varchar2(100);
        o_plsql_entry_subprogram_id   varchar2(100);
        o_plsql_object_id             varchar2(100);
        o_plsql_subprogram_id         varchar2(100);
        o_module                      varchar2(100);
        o_action                      varchar2(100);
        o_client_identifier           varchar2(100);
        o_service_name                varchar2(100);
        o_con_id                      varchar2(100);

        -- helper local vars
        l_ash_grouping                number := 0;
        l_output_line                 varchar2(4000);
        l_ash_header_line             varchar2(4000);
  
    begin

      -- bail out if no ASH samples recorded
      if g_ash.count = 0 then 
          output('    <No active sessions captured during the sampling period>');
          return;
      end if;


      l_ash_header_line := '';
      if output_actses     = 1 then l_ash_header_line := l_ash_header_line || '  ActSes'; end if;
      if output_actses_pct = 1 then l_ash_header_line := l_ash_header_line || '   %Thread'; end if;

      -- ash,ash1,ash2,ash3,ash4,ash5,ash6 parameter column group tokenizer
      for s in (
          SELECT LEVEL
                 , SUBSTR
                   ( TOKEN
                    , DECODE(LEVEL, 1, 1, INSTR(TOKEN, DELIMITER, 1, LEVEL-1)+1)
                    , INSTR(TOKEN, DELIMITER, 1, LEVEL) -
                   DECODE(LEVEL, 1, 1, INSTR(TOKEN, DELIMITER, 1, LEVEL-1)+1)
                   ) TOKEN
          FROM ( SELECT REPLACE(  LOWER(p_ash_columns)  ,' ','')||'+' AS TOKEN
                 , '+'                        AS DELIMITER
                 FROM DUAL
          )
          CONNECT BY 
              INSTR(TOKEN, DELIMITER, 1, LEVEL)>0
          ORDER BY 
              LEVEL ASC
      ) loop
          -- supported ASH column names
          case s.token
              -- actual column names in gv$session
              when 'inst_id'                      then l_ash_grouping := l_ash_grouping + c_inst_id                  ; l_ash_header_line := l_ash_header_line || ' | ' || lpad('INST_ID'                   , w_inst_id                  , ' ');
              when 'con_id'                       then l_ash_grouping := l_ash_grouping + c_con_id                   ; l_ash_header_line := l_ash_header_line || ' | ' || lpad('CON_ID'                     , w_con_id                  , ' ');
              when 'sid'                          then l_ash_grouping := l_ash_grouping + c_sid                      ; l_ash_header_line := l_ash_header_line || ' | ' || lpad('SID'                       , w_sid                      , ' ');
              when 'username'                     then l_ash_grouping := l_ash_grouping + c_username                 ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('USERNAME'                  , w_username                 , ' ');
              when 'machine'                      then l_ash_grouping := l_ash_grouping + c_machine                  ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('MACHINE'                   , w_machine                  , ' ');
              when 'terminal'                     then l_ash_grouping := l_ash_grouping + c_terminal                 ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('TERMINAL'                  , w_terminal                 , ' ');
              when 'program'                      then l_ash_grouping := l_ash_grouping + c_program                  ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('PROGRAM'                   , w_program                  , ' ');
              when 'event'                        then l_ash_grouping := l_ash_grouping + c_event                    ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('EVENT'                     , w_event                    , ' ');
              when 'wait_class'                   then l_ash_grouping := l_ash_grouping + c_wait_class               ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('WAIT_CLASS'                , w_wait_class               , ' ');
              when 'state'                        then l_ash_grouping := l_ash_grouping + c_state                    ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('STATE'                     , w_state                    , ' ');
              when 'p1'                           then l_ash_grouping := l_ash_grouping + c_p1                       ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('P1'                        , w_p1                       , ' ');
              when 'p2'                           then l_ash_grouping := l_ash_grouping + c_p2                       ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('P2'                        , w_p2                       , ' ');
              when 'p3'                           then l_ash_grouping := l_ash_grouping + c_p3                       ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('P3'                        , w_p3                       , ' ');
              when 'row_wait_obj#'                then l_ash_grouping := l_ash_grouping + c_row_wait_obj#            ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('ROW_WAIT_OBJ#'             , w_row_wait_obj#            , ' ');
              when 'row_wait_file#'               then l_ash_grouping := l_ash_grouping + c_row_wait_file#           ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('ROW_WAIT_FILE#'            , w_row_wait_file#           , ' ');
              when 'row_wait_block#'              then l_ash_grouping := l_ash_grouping + c_row_wait_block#          ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('ROW_WAIT_BLOCK#'           , w_row_wait_block#          , ' ');
              when 'row_wait_row#'                then l_ash_grouping := l_ash_grouping + c_row_wait_row#            ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('ROW_WAIT_ROW#'             , w_row_wait_row#            , ' ');
              when 'blocking_session_status'      then l_ash_grouping := l_ash_grouping + c_blocking_session_status  ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('BLOCKING_SESSION_STATUS'   , w_blocking_session_status  , ' ');
              when 'blocking_instance'            then l_ash_grouping := l_ash_grouping + c_blocking_instance        ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('BLOCKING_INSTANCE'         , w_blocking_instance        , ' ');
              when 'blocking_session'             then l_ash_grouping := l_ash_grouping + c_blocking_session         ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('BLOCKING_SESSION'          , w_blocking_session         , ' ');
              when 'sql_hash_value'               then l_ash_grouping := l_ash_grouping + c_sql_hash_value           ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('SQL_HASH_VALUE'            , w_sql_hash_value           , ' ');
              when 'sql_id'                       then l_ash_grouping := l_ash_grouping + c_sql_id                   ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('SQL_ID'                    , w_sql_id                   , ' ');
              when 'sql_child_number'             then l_ash_grouping := l_ash_grouping + c_sql_child_number         ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('SQL_CHILD_NUMBER'          , w_sql_child_number         , ' ');
              when 'plsql_entry_object_id'        then l_ash_grouping := l_ash_grouping + c_plsql_entry_object_id    ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('PLSQL_ENTRY_OBJECT_ID'     , w_plsql_entry_object_id    , ' ');
              when 'plsql_entry_subprogram_id'    then l_ash_grouping := l_ash_grouping + c_plsql_entry_subprogram_id; l_ash_header_line := l_ash_header_line || ' | ' || rpad('PLSQL_ENTRY_SUBPROGRAM_ID' , w_plsql_entry_subprogram_id, ' ');
              when 'plsql_object_id'              then l_ash_grouping := l_ash_grouping + c_plsql_object_id          ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('PLSQL_OBJECT_ID'           , w_plsql_object_id          , ' ');
              when 'plsql_subprogram_id'          then l_ash_grouping := l_ash_grouping + c_plsql_subprogram_id      ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('PLSQL_SUBPROGRAM_ID'       , w_plsql_subprogram_id      , ' ');
              when 'module'                       then l_ash_grouping := l_ash_grouping + c_module                   ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('MODULE'                    , w_module                   , ' ');
              when 'action'                       then l_ash_grouping := l_ash_grouping + c_action                   ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('ACTION'                    , w_action                   , ' ');
              when 'client_identifier'            then l_ash_grouping := l_ash_grouping + c_client_identifier        ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('CLIENT_IDENTIFIER'         , w_client_identifier        , ' ');
              when 'service_name'                 then l_ash_grouping := l_ash_grouping + c_service_name             ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('SERVICE_NAME'              , w_service_name             , ' ');
              -- aliases for convenience (only either real name or alias should be used together at the same time)
              when 'user'                         then l_ash_grouping := l_ash_grouping + c_username                 ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('USERNAME'                  , w_username                 , ' ');
              when 'obj'                          then l_ash_grouping := l_ash_grouping + c_row_wait_obj#            ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('ROW_WAIT_OBJ#'             , w_row_wait_obj#            , ' ');
              when 'file'                         then l_ash_grouping := l_ash_grouping + c_row_wait_file#           ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('ROW_WAIT_FILE#'            , w_row_wait_file#           , ' ');
              when 'block'                        then l_ash_grouping := l_ash_grouping + c_row_wait_block#          ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('ROW_WAIT_BLOCK#'           , w_row_wait_block#          , ' ');
              when 'row'                          then l_ash_grouping := l_ash_grouping + c_row_wait_row#            ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('ROW_WAIT_ROW#'             , w_row_wait_row#            , ' ');
              when 'bss'                          then l_ash_grouping := l_ash_grouping + c_blocking_session_status  ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('BLOCKING_SESSION_STATUS'   , w_blocking_session_status  , ' ');
              when 'bsi'                          then l_ash_grouping := l_ash_grouping + c_blocking_instance        ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('BLOCKING_INSTANCE'         , w_blocking_instance        , ' ');
              when 'bs'                           then l_ash_grouping := l_ash_grouping + c_blocking_session         ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('BLOCKING_SESSION'          , w_blocking_session         , ' ');
              when 'sql'                          then l_ash_grouping := l_ash_grouping + c_sql_hash_value           ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('SQL_HASH_VALUE'            , w_sql_hash_value           , ' ');
              when 'sqlid'                        then l_ash_grouping := l_ash_grouping + c_sql_id                   ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('SQL_ID'                    , w_sql_id                   , ' ');
              when 'child'                        then l_ash_grouping := l_ash_grouping + c_sql_child_number         ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('SQL_CHILD_NUMBER'          , w_sql_child_number         , ' ');
              when 'plsql_eoid'                   then l_ash_grouping := l_ash_grouping + c_plsql_entry_object_id    ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('PLSQL_ENTRY_OBJECT_ID'     , w_plsql_entry_object_id    , ' ');
              when 'plsql_esubpid'                then l_ash_grouping := l_ash_grouping + c_plsql_entry_subprogram_id; l_ash_header_line := l_ash_header_line || ' | ' || rpad('PLSQL_ENTRY_SUBPROGRAM_ID' , w_plsql_entry_subprogram_id, ' ');
              when 'plsql_oid'                    then l_ash_grouping := l_ash_grouping + c_plsql_object_id          ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('PLSQL_OBJECT_ID'           , w_plsql_object_id          , ' ');
              when 'plsql_subpid'                 then l_ash_grouping := l_ash_grouping + c_plsql_subprogram_id      ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('PLSQL_SUBPROGRAM_ID'       , w_plsql_subprogram_id      , ' ');
              when 'mod'                          then l_ash_grouping := l_ash_grouping + c_module                   ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('MODULE'                    , w_module                   , ' ');
              when 'act'                          then l_ash_grouping := l_ash_grouping + c_action                   ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('ACTION'                    , w_action                   , ' ');
              when 'cid'                          then l_ash_grouping := l_ash_grouping + c_client_identifier        ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('CLIENT_IDENTIFIER'         , w_client_identifier        , ' ');
              when 'service'                      then l_ash_grouping := l_ash_grouping + c_service_name             ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('SERVICE_NAME'              , w_service_name             , ' ');
              when 'wait_event'                   then l_ash_grouping := l_ash_grouping + c_event                    ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('EVENT'                     , w_event                    , ' ');
              when 'wait_state'                   then l_ash_grouping := l_ash_grouping + c_state                    ; l_ash_header_line := l_ash_header_line || ' | ' || rpad('STATE'                     , w_state                    , ' ');
          else
              null;
              raise_application_error(-20001, 'Snapper: Invalid ASH column name, search for "ASH column name"'||chr(10)||'in snapper.sql script to see supported column names.'||chr(10)||sqlerrm);
          end case; -- case s.token

      end loop; -- tokenizer

      output(' ');
      output(lpad('-',length(l_ash_header_line),'-'));
      output(l_ash_header_line);
      output(lpad('-',length(l_ash_header_line),'-'));

      -- this is needed for "easy" sorting and group by ops (without any custom stored object types!)
      for i in (
          with /* get_aggregates_from_ash */ raw_records as (
             select column_value rec from table(cast(g_ash as sys.dbms_debug_vc2coll))
          ),
          ash_records as (
             select 
                 substr(r.rec, instr(r.rec, '<', 1,  1)+1, instr (substr(r.rec, instr(r.rec, '<', 1,  1)+1), '>')-1) inst_id
               , substr(r.rec, instr(r.rec, '<', 1,  2)+1, instr (substr(r.rec, instr(r.rec, '<', 1,  2)+1), '>')-1) sid
               , substr(r.rec, instr(r.rec, '<', 1,  3)+1, instr (substr(r.rec, instr(r.rec, '<', 1,  3)+1), '>')-1) username
               , substr(r.rec, instr(r.rec, '<', 1,  4)+1, instr (substr(r.rec, instr(r.rec, '<', 1,  4)+1), '>')-1) machine
               , substr(r.rec, instr(r.rec, '<', 1,  5)+1, instr (substr(r.rec, instr(r.rec, '<', 1,  5)+1), '>')-1) terminal
               , substr(r.rec, instr(r.rec, '<', 1,  6)+1, instr (substr(r.rec, instr(r.rec, '<', 1,  6)+1), '>')-1) program
               , substr(r.rec, instr(r.rec, '<', 1,  7)+1, instr (substr(r.rec, instr(r.rec, '<', 1,  7)+1), '>')-1) event
               , substr(r.rec, instr(r.rec, '<', 1,  8)+1, instr (substr(r.rec, instr(r.rec, '<', 1,  8)+1), '>')-1) wait_class
               , substr(r.rec, instr(r.rec, '<', 1,  9)+1, instr (substr(r.rec, instr(r.rec, '<', 1,  9)+1), '>')-1) state
               , substr(r.rec, instr(r.rec, '<', 1, 10)+1, instr (substr(r.rec, instr(r.rec, '<', 1, 10)+1), '>')-1) p1
               , substr(r.rec, instr(r.rec, '<', 1, 11)+1, instr (substr(r.rec, instr(r.rec, '<', 1, 11)+1), '>')-1) p2
               , substr(r.rec, instr(r.rec, '<', 1, 12)+1, instr (substr(r.rec, instr(r.rec, '<', 1, 12)+1), '>')-1) p3
               , substr(r.rec, instr(r.rec, '<', 1, 13)+1, instr (substr(r.rec, instr(r.rec, '<', 1, 13)+1), '>')-1) row_wait_obj#
               , substr(r.rec, instr(r.rec, '<', 1, 14)+1, instr (substr(r.rec, instr(r.rec, '<', 1, 14)+1), '>')-1) row_wait_file#
               , substr(r.rec, instr(r.rec, '<', 1, 15)+1, instr (substr(r.rec, instr(r.rec, '<', 1, 15)+1), '>')-1) row_wait_block#
               , substr(r.rec, instr(r.rec, '<', 1, 16)+1, instr (substr(r.rec, instr(r.rec, '<', 1, 16)+1), '>')-1) row_wait_row#
               , substr(r.rec, instr(r.rec, '<', 1, 17)+1, instr (substr(r.rec, instr(r.rec, '<', 1, 17)+1), '>')-1) blocking_session_status
               , substr(r.rec, instr(r.rec, '<', 1, 18)+1, instr (substr(r.rec, instr(r.rec, '<', 1, 18)+1), '>')-1) blocking_instance
               , substr(r.rec, instr(r.rec, '<', 1, 19)+1, instr (substr(r.rec, instr(r.rec, '<', 1, 19)+1), '>')-1) blocking_session
               , substr(r.rec, instr(r.rec, '<', 1, 20)+1, instr (substr(r.rec, instr(r.rec, '<', 1, 20)+1), '>')-1) sql_hash_value
               , substr(r.rec, instr(r.rec, '<', 1, 21)+1, instr (substr(r.rec, instr(r.rec, '<', 1, 21)+1), '>')-1) sql_id
               , substr(r.rec, instr(r.rec, '<', 1, 22)+1, instr (substr(r.rec, instr(r.rec, '<', 1, 22)+1), '>')-1) sql_child_number
               , substr(r.rec, instr(r.rec, '<', 1, 23)+1, instr (substr(r.rec, instr(r.rec, '<', 1, 23)+1), '>')-1) plsql_entry_object_id
               , substr(r.rec, instr(r.rec, '<', 1, 24)+1, instr (substr(r.rec, instr(r.rec, '<', 1, 24)+1), '>')-1) plsql_entry_subprogram_id
               , substr(r.rec, instr(r.rec, '<', 1, 25)+1, instr (substr(r.rec, instr(r.rec, '<', 1, 25)+1), '>')-1) plsql_object_id
               , substr(r.rec, instr(r.rec, '<', 1, 26)+1, instr (substr(r.rec, instr(r.rec, '<', 1, 26)+1), '>')-1) plsql_subprogram_id
               , substr(r.rec, instr(r.rec, '<', 1, 27)+1, instr (substr(r.rec, instr(r.rec, '<', 1, 27)+1), '>')-1) module
               , substr(r.rec, instr(r.rec, '<', 1, 28)+1, instr (substr(r.rec, instr(r.rec, '<', 1, 28)+1), '>')-1) action
               , substr(r.rec, instr(r.rec, '<', 1, 29)+1, instr (substr(r.rec, instr(r.rec, '<', 1, 29)+1), '>')-1) client_identifier
               , substr(r.rec, instr(r.rec, '<', 1, 30)+1, instr (substr(r.rec, instr(r.rec, '<', 1, 30)+1), '>')-1) service_name              
               , substr(r.rec, instr(r.rec, '<', 1, 31)+1, instr (substr(r.rec, instr(r.rec, '<', 1, 31)+1), '>')-1) con_id              
             from 
                raw_records r
          )
          select * from (
            select
                 decode(bitand(l_ash_grouping, power(2, s_inst_id                       )), 0, chr(0), inst_id                       ) as inst_id
               , decode(bitand(l_ash_grouping, power(2, s_sid                           )), 0, chr(0), sid                           ) as sid                           
               , decode(bitand(l_ash_grouping, power(2, s_username                      )), 0, chr(0), username                      ) as username                      
               , decode(bitand(l_ash_grouping, power(2, s_machine                       )), 0, chr(0), machine                       ) as machine                       
               , decode(bitand(l_ash_grouping, power(2, s_terminal                      )), 0, chr(0), terminal                      ) as terminal                      
               , decode(bitand(l_ash_grouping, power(2, s_program                       )), 0, chr(0), program                       ) as program                       
               , decode(bitand(l_ash_grouping, power(2, s_event                         )), 0, chr(0), event                         ) as event                         
               , decode(bitand(l_ash_grouping, power(2, s_wait_class                    )), 0, chr(0), wait_class                    ) as wait_class                    
               , decode(bitand(l_ash_grouping, power(2, s_state                         )), 0, chr(0), state                         ) as state                         
               , decode(bitand(l_ash_grouping, power(2, s_p1                            )), 0, chr(0), p1                            ) as p1                            
               , decode(bitand(l_ash_grouping, power(2, s_p2                            )), 0, chr(0), p2                            ) as p2                            
               , decode(bitand(l_ash_grouping, power(2, s_p3                            )), 0, chr(0), p3                            ) as p3                            
               , decode(bitand(l_ash_grouping, power(2, s_row_wait_obj#                 )), 0, chr(0), row_wait_obj#                 ) as row_wait_obj#                 
               , decode(bitand(l_ash_grouping, power(2, s_row_wait_file#                )), 0, chr(0), row_wait_file#                ) as row_wait_file#                
               , decode(bitand(l_ash_grouping, power(2, s_row_wait_block#               )), 0, chr(0), row_wait_block#               ) as row_wait_block#               
               , decode(bitand(l_ash_grouping, power(2, s_row_wait_row#                 )), 0, chr(0), row_wait_row#                 ) as row_wait_row#                 
               , decode(bitand(l_ash_grouping, power(2, s_blocking_session_status       )), 0, chr(0), blocking_session_status       ) as blocking_session_status       
               , decode(bitand(l_ash_grouping, power(2, s_blocking_instance             )), 0, chr(0), blocking_instance             ) as blocking_instance             
               , decode(bitand(l_ash_grouping, power(2, s_blocking_session              )), 0, chr(0), blocking_session              ) as blocking_session              
               , decode(bitand(l_ash_grouping, power(2, s_sql_hash_value                )), 0, chr(0), sql_hash_value                ) as sql_hash_value                
               , decode(bitand(l_ash_grouping, power(2, s_sql_id                        )), 0, chr(0), sql_id                        ) as sql_id                        
               , decode(bitand(l_ash_grouping, power(2, s_sql_child_number              )), 0, chr(0), sql_child_number              ) as sql_child_number              
               , decode(bitand(l_ash_grouping, power(2, s_plsql_entry_object_id         )), 0, chr(0), plsql_entry_object_id         ) as plsql_entry_object_id         
               , decode(bitand(l_ash_grouping, power(2, s_plsql_entry_subprogram_id     )), 0, chr(0), plsql_entry_subprogram_id     ) as plsql_entry_subprogram_id     
               , decode(bitand(l_ash_grouping, power(2, s_plsql_object_id               )), 0, chr(0), plsql_object_id               ) as plsql_object_id               
               , decode(bitand(l_ash_grouping, power(2, s_plsql_subprogram_id           )), 0, chr(0), plsql_subprogram_id           ) as plsql_subprogram_id           
               , decode(bitand(l_ash_grouping, power(2, s_module                        )), 0, chr(0), module                        ) as module                        
               , decode(bitand(l_ash_grouping, power(2, s_action                        )), 0, chr(0), action                        ) as action                        
               , decode(bitand(l_ash_grouping, power(2, s_client_identifier             )), 0, chr(0), client_identifier             ) as client_identifier             
               , decode(bitand(l_ash_grouping, power(2, s_service_name                  )), 0, chr(0), service_name                  ) as service_name                  
               , decode(bitand(l_ash_grouping, power(2, s_con_id                        )), 0, chr(0), con_id                        ) as con_id                  
               , count(*)/g_ash_samples_taken average_active_samples
            from
               ash_records a
            group by
                 decode(bitand(l_ash_grouping, power(2, s_inst_id                       )), 0, chr(0), inst_id                       ) -- inst_id                       
               , decode(bitand(l_ash_grouping, power(2, s_sid                           )), 0, chr(0), sid                           ) -- sid                           
               , decode(bitand(l_ash_grouping, power(2, s_username                      )), 0, chr(0), username                      ) -- username                      
               , decode(bitand(l_ash_grouping, power(2, s_machine                       )), 0, chr(0), machine                       ) -- machine                       
               , decode(bitand(l_ash_grouping, power(2, s_terminal                      )), 0, chr(0), terminal                      ) -- terminal                      
               , decode(bitand(l_ash_grouping, power(2, s_program                       )), 0, chr(0), program                       ) -- program                       
               , decode(bitand(l_ash_grouping, power(2, s_event                         )), 0, chr(0), event                         ) -- event                         
               , decode(bitand(l_ash_grouping, power(2, s_wait_class                    )), 0, chr(0), wait_class                    ) -- wait_class                    
               , decode(bitand(l_ash_grouping, power(2, s_state                         )), 0, chr(0), state                         ) -- state                         
               , decode(bitand(l_ash_grouping, power(2, s_p1                            )), 0, chr(0), p1                            ) -- p1                            
               , decode(bitand(l_ash_grouping, power(2, s_p2                            )), 0, chr(0), p2                            ) -- p2                            
               , decode(bitand(l_ash_grouping, power(2, s_p3                            )), 0, chr(0), p3                            ) -- p3                            
               , decode(bitand(l_ash_grouping, power(2, s_row_wait_obj#                 )), 0, chr(0), row_wait_obj#                 ) -- row_wait_obj#                 
               , decode(bitand(l_ash_grouping, power(2, s_row_wait_file#                )), 0, chr(0), row_wait_file#                ) -- row_wait_file#                
               , decode(bitand(l_ash_grouping, power(2, s_row_wait_block#               )), 0, chr(0), row_wait_block#               ) -- row_wait_block#               
               , decode(bitand(l_ash_grouping, power(2, s_row_wait_row#                 )), 0, chr(0), row_wait_row#                 ) -- row_wait_row#                 
               , decode(bitand(l_ash_grouping, power(2, s_blocking_session_status       )), 0, chr(0), blocking_session_status       ) -- blocking_session_status       
               , decode(bitand(l_ash_grouping, power(2, s_blocking_instance             )), 0, chr(0), blocking_instance             ) -- blocking_instance             
               , decode(bitand(l_ash_grouping, power(2, s_blocking_session              )), 0, chr(0), blocking_session              ) -- blocking_session              
               , decode(bitand(l_ash_grouping, power(2, s_sql_hash_value                )), 0, chr(0), sql_hash_value                ) -- sql_hash_value                
               , decode(bitand(l_ash_grouping, power(2, s_sql_id                        )), 0, chr(0), sql_id                        ) -- sql_id                        
               , decode(bitand(l_ash_grouping, power(2, s_sql_child_number              )), 0, chr(0), sql_child_number              ) -- sql_child_number              
               , decode(bitand(l_ash_grouping, power(2, s_plsql_entry_object_id         )), 0, chr(0), plsql_entry_object_id         ) -- plsql_entry_object_id         
               , decode(bitand(l_ash_grouping, power(2, s_plsql_entry_subprogram_id     )), 0, chr(0), plsql_entry_subprogram_id     ) -- plsql_entry_subprogram_id     
               , decode(bitand(l_ash_grouping, power(2, s_plsql_object_id               )), 0, chr(0), plsql_object_id               ) -- plsql_object_id               
               , decode(bitand(l_ash_grouping, power(2, s_plsql_subprogram_id           )), 0, chr(0), plsql_subprogram_id           ) -- plsql_subprogram_id           
               , decode(bitand(l_ash_grouping, power(2, s_module                        )), 0, chr(0), module                        ) -- module                        
               , decode(bitand(l_ash_grouping, power(2, s_action                        )), 0, chr(0), action                        ) -- action                        
               , decode(bitand(l_ash_grouping, power(2, s_client_identifier             )), 0, chr(0), client_identifier             ) -- client_identifier             
               , decode(bitand(l_ash_grouping, power(2, s_service_name                  )), 0, chr(0), service_name                  ) -- service_name                  
               , decode(bitand(l_ash_grouping, power(2, s_con_id                        )), 0, chr(0), con_id                        ) -- con_id                  
           order by
              count(*)/g_ash_samples_taken desc
          )
          where rownum <= p_topn
      ) loop

          l_output_line := '';

          o_inst_id                     := CASE WHEN i.inst_id                        = chr(0) THEN null ELSE nvl(i.inst_id                       , ' ') END;
          o_sid                         := CASE WHEN i.sid                            = chr(0) THEN null ELSE nvl(i.sid                           , ' ') END;
          o_username                    := CASE WHEN i.username                       = chr(0) THEN null ELSE nvl(i.username                      , ' ') END;
          o_machine                     := CASE WHEN i.machine                        = chr(0) THEN null ELSE nvl(i.machine                       , ' ') END;
          o_terminal                    := CASE WHEN i.terminal                       = chr(0) THEN null ELSE nvl(i.terminal                      , ' ') END;
          o_program                     := CASE WHEN i.program                        = chr(0) THEN null ELSE nvl(i.program                       , ' ') END;
          o_event                       := CASE WHEN i.event                          = chr(0) THEN null ELSE nvl(i.event                         , ' ') END;
          o_wait_class                  := CASE WHEN i.wait_class                     = chr(0) THEN null ELSE nvl(i.wait_class                    , ' ') END;
          o_state                       := CASE WHEN i.state                          = chr(0) THEN null ELSE nvl(i.state                         , ' ') END;
          o_p1                          := CASE WHEN i.p1                             = chr(0) THEN null ELSE nvl(i.p1                            , ' ') END;
          o_p2                          := CASE WHEN i.p2                             = chr(0) THEN null ELSE nvl(i.p2                            , ' ') END;
          o_p3                          := CASE WHEN i.p3                             = chr(0) THEN null ELSE nvl(i.p3                            , ' ') END;
          o_row_wait_obj#               := CASE WHEN i.row_wait_obj#                  = chr(0) THEN null ELSE nvl(i.row_wait_obj#                 , ' ') END;
          o_row_wait_file#              := CASE WHEN i.row_wait_file#                 = chr(0) THEN null ELSE nvl(i.row_wait_file#                , ' ') END;
          o_row_wait_block#             := CASE WHEN i.row_wait_block#                = chr(0) THEN null ELSE nvl(i.row_wait_block#               , ' ') END;
          o_row_wait_row#               := CASE WHEN i.row_wait_row#                  = chr(0) THEN null ELSE nvl(i.row_wait_row#                 , ' ') END;
          o_blocking_session_status     := CASE WHEN i.blocking_session_status        = chr(0) THEN null ELSE nvl(i.blocking_session_status       , ' ') END;
          o_blocking_instance           := CASE WHEN i.blocking_instance              = chr(0) THEN null ELSE nvl(i.blocking_instance             , ' ') END;
          o_blocking_session            := CASE WHEN i.blocking_session               = chr(0) THEN null ELSE nvl(i.blocking_session              , ' ') END;
          o_sql_hash_value              := CASE WHEN i.sql_hash_value                 = chr(0) THEN null ELSE nvl(i.sql_hash_value                , ' ') END;
          o_sql_id                      := CASE WHEN i.sql_id                         = chr(0) THEN null ELSE nvl(i.sql_id                        , ' ') END;
          o_sql_child_number            := CASE WHEN i.sql_child_number               = chr(0) THEN null ELSE nvl(i.sql_child_number              , ' ') END;
          o_plsql_entry_object_id       := CASE WHEN i.plsql_entry_object_id          = chr(0) THEN null ELSE nvl(i.plsql_entry_object_id         , ' ') END;
          o_plsql_entry_subprogram_id   := CASE WHEN i.plsql_entry_subprogram_id      = chr(0) THEN null ELSE nvl(i.plsql_entry_subprogram_id     , ' ') END;
          o_plsql_object_id             := CASE WHEN i.plsql_object_id                = chr(0) THEN null ELSE nvl(i.plsql_object_id               , ' ') END;
          o_plsql_subprogram_id         := CASE WHEN i.plsql_subprogram_id            = chr(0) THEN null ELSE nvl(i.plsql_subprogram_id           , ' ') END;
          o_module                      := CASE WHEN i.module                         = chr(0) THEN null ELSE nvl(i.module                        , ' ') END;
          o_action                      := CASE WHEN i.action                         = chr(0) THEN null ELSE nvl(i.action                        , ' ') END;
          o_client_identifier           := CASE WHEN i.client_identifier              = chr(0) THEN null ELSE nvl(i.client_identifier             , ' ') END;
          o_service_name                := CASE WHEN i.service_name                   = chr(0) THEN null ELSE nvl(i.service_name                  , ' ') END;
          o_con_id                      := CASE WHEN i.con_id                         = chr(0) THEN null ELSE nvl(i.con_id                        , ' ') END;

          -- print the AAS and activity % as the first columns
          l_output_line := '';
          if output_actses     = 1 then l_output_line := l_output_line || lpad(to_char(round(i.average_active_samples,2),'9999.99'), w_actses, ' '); end if;
          if output_actses_pct = 1 then l_output_line := l_output_line || lpad('('||to_char(round(i.average_active_samples*100))||'%)', w_actses_pct, ' '); end if;

          -- loop through ash columns to find what to print and in which order
          for s in (
              SELECT LEVEL
                     , SUBSTR
                       ( TOKEN
                        , DECODE(LEVEL, 1, 1, INSTR(TOKEN, DELIMITER, 1, LEVEL-1)+1)
                        , INSTR(TOKEN, DELIMITER, 1, LEVEL) -
                       DECODE(LEVEL, 1, 1, INSTR(TOKEN, DELIMITER, 1, LEVEL-1)+1)
                       ) TOKEN
              FROM ( SELECT REPLACE(  LOWER(p_ash_columns)  ,' ','')||'+' AS TOKEN
                     , '+'                        AS DELIMITER
                     FROM DUAL
              )
              CONNECT BY 
                  INSTR(TOKEN, DELIMITER, 1, LEVEL)>0 
              ORDER BY 
                  LEVEL ASC
          ) loop
              l_output_line := l_output_line || ' | ' ||
                  case s.token
                      -- actual column names in gv$session
                      when 'inst_id'                      then lpad(o_inst_id                   , w_inst_id                  , ' ')
                      when 'con_id'                       then lpad(o_con_id                    , w_con_id                   , ' ')
                      when 'sid'                          then lpad(o_sid                       , w_sid                      , ' ')
                      when 'username'                     then rpad(o_username                  , w_username                 , ' ')
                      when 'machine'                      then rpad(o_machine                   , w_machine                  , ' ')
                      when 'terminal'                     then rpad(o_terminal                  , w_terminal                 , ' ')
                      when 'program'                      then rpad(o_program                   , w_program                  , ' ')
                      when 'event'                        then rpad(o_event                     , w_event                    , ' ')
                      when 'wait_class'                   then rpad(o_wait_class                , w_wait_class               , ' ')
                      when 'state'                        then rpad(o_state                     , w_state                    , ' ')
                      when 'p1'                           then rpad(o_p1                        , w_p1                       , ' ')
                      when 'p2'                           then rpad(o_p2                        , w_p2                       , ' ')
                      when 'p3'                           then rpad(o_p3                        , w_p3                       , ' ')
                      when 'row_wait_obj#'                then rpad(o_row_wait_obj#             , w_row_wait_obj#            , ' ')
                      when 'row_wait_file#'               then rpad(o_row_wait_file#            , w_row_wait_file#           , ' ')
                      when 'row_wait_block#'              then rpad(o_row_wait_block#           , w_row_wait_block#          , ' ')
                      when 'row_wait_row#'                then rpad(o_row_wait_row#             , w_row_wait_row#            , ' ')
                      when 'blocking_session_status'      then rpad(o_blocking_session_status   , w_blocking_session_status  , ' ')
                      when 'blocking_instance'            then rpad(o_blocking_instance         , w_blocking_instance        , ' ')
                      when 'blocking_session'             then rpad(o_blocking_session          , w_blocking_session         , ' ')
                      when 'sql_hash_value'               then rpad(o_sql_hash_value            , w_sql_hash_value           , ' ')
                      when 'sql_id'                       then rpad(o_sql_id                    , w_sql_id                   , ' ')
                      when 'sql_child_number'             then rpad(o_sql_child_number          , w_sql_child_number         , ' ')
                      when 'plsql_entry_object_id'        then rpad(o_plsql_entry_object_id     , w_plsql_entry_object_id    , ' ')
                      when 'plsql_entry_subprogram_id'    then rpad(o_plsql_entry_subprogram_id , w_plsql_entry_subprogram_id, ' ')
                      when 'plsql_object_id'              then rpad(o_plsql_object_id           , w_plsql_object_id          , ' ')
                      when 'plsql_subprogram_id'          then rpad(o_plsql_subprogram_id       , w_plsql_subprogram_id      , ' ')
                      when 'module'                       then rpad(o_module                    , w_module                   , ' ')
                      when 'action'                       then rpad(o_action                    , w_action                   , ' ')
                      when 'client_identifier'            then rpad(o_client_identifier         , w_client_identifier        , ' ')
                      when 'service_name'                 then rpad(o_service_name              , w_service_name             , ' ')
                      -- aliases for convenience (only either real name or alias should be used together at the same time) 
                      when 'user'                         then rpad(o_username                  , w_username                 , ' ')
                      when 'obj'                          then rpad(o_row_wait_obj#             , w_row_wait_obj#            , ' ')
                      when 'file'                         then rpad(o_row_wait_file#            , w_row_wait_file#           , ' ')
                      when 'block'                        then rpad(o_row_wait_block#           , w_row_wait_block#          , ' ')
                      when 'row'                          then rpad(o_row_wait_row#             , w_row_wait_row#            , ' ')
                      when 'bss'                          then rpad(o_blocking_session_status   , w_blocking_session_status  , ' ')
                      when 'bsi'                          then rpad(o_blocking_instance         , w_blocking_instance        , ' ')
                      when 'bs'                           then rpad(o_blocking_session          , w_blocking_session         , ' ')
                      when 'sql'                          then rpad(o_sql_hash_value            , w_sql_hash_value           , ' ')
                      when 'sqlid'                        then rpad(o_sql_id                    , w_sql_id                   , ' ')
                      when 'child'                        then rpad(o_sql_child_number          , w_sql_child_number         , ' ')
                      when 'plsql_eoid'                   then rpad(o_plsql_entry_object_id     , w_plsql_entry_object_id    , ' ')
                      when 'plsql_esubpid'                then rpad(o_plsql_entry_subprogram_id , w_plsql_entry_subprogram_id, ' ')
                      when 'plsql_oid'                    then rpad(o_plsql_object_id           , w_plsql_object_id          , ' ')
                      when 'plsql_subpid'                 then rpad(o_plsql_subprogram_id       , w_plsql_subprogram_id      , ' ')
                      when 'mod'                          then rpad(o_module                    , w_module                   , ' ')
                      when 'act'                          then rpad(o_action                    , w_action                   , ' ')
                      when 'cid'                          then rpad(o_client_identifier         , w_client_identifier        , ' ')
                      when 'service'                      then rpad(o_service_name              , w_service_name             , ' ')
                      when 'wait_event'                   then rpad(o_event                     , w_event                    , ' ')
                      when 'wait_state'                   then rpad(o_state                     , w_state                    , ' ')
                  else
                      ''
                  end; -- case s.token

          end loop; -- ash parameter tokenizer

          output(l_output_line);

      end loop; -- grouped ash samples

  end out_ash;


-- and it begins!!!
begin

    -- get snappers own sid into g_mysid
    select sid into g_mysid from v$mystat where rownum = 1;

    pagesize := nvl( getopt('&snapper_options', 'pagesize=' ), pagesize);
    --output ( 'Pagesize='||pagesize );

    lv_ash   := getopt('&snapper_options', 'ash');
    lv_stats := getopt('&snapper_options', 'stat');

    if lv_ash is not null then gather_ash := 1; end if;
    if lv_stats is not null then gather_stats := 1; end if;

    --output('all='||case when getopt('&snapper_options', 'all') = chr(0) then 'chr(0)' when getopt('&snapper_options', 'all') is null then 'null' else (getopt('&snapper_options','all')) end);
    -- some additional default value logic
    if getopt('&snapper_options', 'all') is not null then
        --output('setting stats to all due to option = all');
        gather_stats := 1;
        gather_ash   := 1;
    else 
        if (lv_ash is null and lv_stats is null) then
            gather_stats := 0;  
            gather_ash   := 1;
        end if;
    end if;

    -- determine which performance counters and stats to collect
    lv_gather := case nvl( lower(getopt ('&snapper_options', 'gather=')), 'stw')
                    when 'all'  then 'stw'
                    else nvl( lower(getopt ('&snapper_options', 'gather=')), 'stw')
                 end;

    --lv_gather:=getopt ('&snapper_options', 'gather=');
    --output('lv_gather='||lv_gather);

    g_snap_begin := lower(getopt('&snapper_options', 'begin' ));
    g_snap_end   := lower(getopt('&snapper_options', 'end' ));
    --output('g_snap_begin = '||g_snap_begin);    
    --output('g_snap_end = '||g_snap_end);    
 
    if pagesize > 0 then
        output(' ');
        output('-- Session Snapper v4.24 - by Tanel Poder ( http://blog.tanelpoder.com/snapper ) - Enjoy the Most Advanced Oracle Troubleshooting Script on the Planet! :)');
        output(' ');
    end if;

    -- initialize statistic and event name array
    -- fetch statistic names with their adjusted IDs
    select /* get_stat_names */ *
    bulk collect into sn_tmp
    from (
                                 select 'STAT' stype, statistic# - pls_adjust statistic#, name
                                 from v$statname
                                 where (lv_gather like '%s%' or lv_gather like '%a%')
                                 --
                                 union all
                                 select 'WAIT',
                                        event# + (select count(*) from v$statname) + 1 - pls_adjust, name
                                 from v$event_name
                                 where (lv_gather like '%w%' or lv_gather like '%a%')
                                 --
                                 union all
                                 select 'TIME' stype, stat_id - pls_adjust statistic#, stat_name name
                                 from gv$sys_time_model
                                 where (lv_gather like '%t%' or lv_gather like '%a%')
                                 --
                                 union all
                                 select 'LATG',
                                       l.latch# +
                                           (select count(*) from v$statname) +
                                           (select count(*) from v$event_name) +
                                           1 - pls_adjust statistic#,
                                       name
                                 from gv$latch l
                                 where (lv_gather like '%l%' or lv_gather like '%a%')
                                 --
            &_IF_X_ACCESSIBLE    union all
            &_IF_X_ACCESSIBLE    select 'BUFG',
            &_IF_X_ACCESSIBLE          indx +
            &_IF_X_ACCESSIBLE              (select count(*) from v$statname) +
            &_IF_X_ACCESSIBLE              (select count(*) from v$event_name) +
            &_IF_X_ACCESSIBLE              (select count(*) from gv$latch) +
            &_IF_X_ACCESSIBLE              1 - pls_adjust statistic#,
            &_IF_X_ACCESSIBLE         kcbwhdes name
            &_IF_X_ACCESSIBLE    from x$kcbwh
            &_IF_X_ACCESSIBLE    where   (lv_gather like '%b%' or lv_gather like '%a%')
                                 --
                                 union all
                                 select 'ENQG',
                                       ascii(substr(e.eq_type,1,1))*256 + ascii(substr(e.eq_type,2,1)) +
                                           (select count(*) from v$statname) +
                                           (select count(*) from v$event_name) +
                                           (select count(*) from gv$latch) +
            &_IF_X_ACCESSIBLE              (select count(*) from x$kcbwh) +
                                           1 - pls_adjust statistic#,
                                           eq_type
                                 from (
                                       select es.eq_type
                                              ||' - '||lt.name
                                              eq_type,
                                              total_req#
                                       from
                                              gv$enqueue_stat es
                                            , gv$lock_type lt
                                       where es.eq_type = lt.type
                                 ) e
                                 where (lv_gather like '%e%' or lv_gather like '%a%')
    ) snapper_statnames
    order by stype, statistic#;

    -- store these into an index_by array organized by statistic# for fast lookup
    for i in 1..sn_tmp.count loop
        sn(sn_tmp(i).statistic#) := sn_tmp(i);
        sn_reverse(sn_tmp(i).stype||','||sn_tmp(i).name) := sn_tmp(i);
    end loop;


    -- main sampling loop
    for c in 1..&snapper_count loop

        -- sesstat and other performance counter sampling
        if gather_stats = 1 then

            -- print header if required
            gv_header_string :=
                      CASE WHEN output_header      = 1 THEN 'HEAD,'                        END
                   || CASE WHEN output_inst        = 1 THEN ' INST,'                       END
                   || CASE WHEN output_sid         = 1 THEN '    SID,'                     END
                   || CASE WHEN output_inst_sid    = 1 THEN ' SID @INST,'                  END
                   || CASE WHEN output_username    = 1 THEN ' USERNAME  ,'                 END
                   || CASE WHEN output_time        = 1 THEN ' SNAPSHOT START   ,'          END
                   || CASE WHEN output_seconds     = 1 THEN '  SECONDS,'                   END
                   || CASE WHEN output_stype       = 1 THEN ' TYPE,'                       END
                   || CASE WHEN output_sname       = 1 THEN rpad(' STATISTIC',59,' ')||',' END
                   || CASE WHEN output_delta       = 1 THEN '         DELTA,'              END
                   || CASE WHEN output_delta_s     = 1 THEN '  DELTA/SEC,'                 END
                   || CASE WHEN output_hdelta      = 1 THEN '     HDELTA,'                 END
                   || CASE WHEN output_hdelta_s    = 1 THEN ' HDELTA/SEC,'                 END
                   || CASE WHEN output_percent     = 1 THEN '    %TIME,'                   END
                   || CASE WHEN output_pcthist     = 1 THEN ' GRAPH       ,'               END
                   || CASE WHEN output_eventcnt    = 1 THEN ' NUM_WAITS,'                  END
                   || CASE WHEN output_eventcnt_s  = 1 THEN '  WAITS/SEC,'                 END
                   || CASE WHEN output_eventavg    = 1 THEN '   AVERAGES                                    ' END
            ;


            if g_snap_begin is null then
                if pagesize > 0 and mod(c-1, pagesize) = 0 then
                    output(rpad('-',length(gv_header_string),'-'));
                    output(gv_header_string);
                    output(rpad('-',length(gv_header_string),'-'));
                else
                    if pagesize = -1 and c = 1 then
                        output(gv_header_string);
                    end if;
                end if;
            else
                output('Taking BEGIN sample ...');
            end if;

            -- TODO raise an error if both begin and end are used together
            -- TODO conditionally comment out the refcursor use unless begin and end is used

            -- manual before/after snapshots (snapper v4)
            if g_snap_begin is not null or g_snap_end is not null then
                if g_snap_begin is not null then
                    get_sessions;
                    snap(d1,s1,l1,g_snap1);
&_MANUAL_SNAPSHOT   open :snapper for select column_value rec from table(g_snap1); -- if you see this error then run: "VAR SNAPPER REFCURSOR" first!
                    exit;
                end if;

                if g_snap_end is not null then
&_MANUAL_SNAPSHOT   fetch :snapper bulk collect into g_snap1; -- You should run snapper with BEGIN option first!
                    -- procedure snap_from_stats_string (p_string_stats in sys.dbms_debug_vc2coll, p_snapdate out date, p_stats out stab, l_stats out ltab)
                    snap_from_stats_string(g_snap1, d1, s1, l1);
                end if;
            else -- normal interval sampling
                if c = 1 then
                    get_sessions;
                    snap(d1,s1,l1,g_snap1);
                else
                    get_sessions;
                    d1 := d2;
                    s1 := s2;
                    g_snap1 := g_snap2;
                end if; -- c = 1
            end if;

        end if; -- gather_stats = 1



        -- ASH style sampling 
&_USE_DBMS_LOCK ash_date1 := sysdate; 
&_USE_DBMS_LOCK if gather_ash = 1 then 
&_USE_DBMS_LOCK     while sysdate < (ash_date1 + (&snapper_sleep/86400)) loop
&_USE_DBMS_LOCK         -- get active session records from g_sessions
&_USE_DBMS_LOCK         get_sessions;
&_USE_DBMS_LOCK         extract_ash();
&_USE_DBMS_LOCK         -- sleep timeout backoff depending on the duration sampled (for up to 10 seconds total sampling time will get max 100 Hz sampling)
&_USE_DBMS_LOCK         -- for longer duration sampling the algorithm will back off and for long durations (over 100 sec) the sampling rate will stabilize
&_USE_DBMS_LOCK         -- at 1Hz
&_USE_DBMS_LOCK         dbms_lock.sleep( greatest(0.1,(least(1,&snapper_sleep*&snapper_count/100))) );
&_USE_DBMS_LOCK     end loop;
&_USE_DBMS_LOCK else
&_USE_DBMS_LOCK     dbms_lock.sleep( ((ash_date1+(&snapper_sleep/86400)) - sysdate)*86400 ); 
&_USE_DBMS_LOCK     null;
&_USE_DBMS_LOCK end if;
&_USE_DBMS_LOCK ash_date2 := sysdate; 

        -- sesstat new sample and delta calculation
        if gather_stats = 1 then

            get_sessions;
            snap(d2,s2,l2,g_snap2);

            -- manually coded nested loop outer join for calculating deltas:
            -- why not use a SQL join? this would require creation of PL/SQL 
            -- collection object types, but Snapper does not require any changes 
            -- to the database, so any custom object types are out! 
            changed_values := 0;
            missing_values_s1 := 0;
            missing_values_s2 := 0;

            -- remember last disappeared SID so we wouldn't need to output a warning 
            -- message for each statistic row of that disappeared sid 
            disappeared_sid := 0;

            i :=1; -- iteration counter (for debugging)
            a :=1; -- s1 array index
            b :=1; -- s2 array index
            
            if s2.count > 0 then lv_curr_sid := s2(b).sid; end if;

            while ( a <= s1.count and b <= s2.count ) loop

                if lv_curr_sid != 0 and lv_curr_sid != s2(b).sid then
                    if pagesize > 0 and mod(c-1, pagesize) = 0 then
                        -- if filtering specific stats, assuming that it's better to not leave spaces between every session data

                        if getopt('&snapper_options', 'sinclude=')||getopt('&snapper_options', 'tinclude=' )||getopt('&snapper_options', 'winclude=' ) is null then
                            output(' ');
                            -- output(rpad('-',length(gv_header_string),'-'));
                            -- output(gv_header_string);
                            -- output(rpad('-',length(gv_header_string),'-'));
                        end if;
                    end if;
                    lv_curr_sid := s2(b).sid;
                end if;

                delta := 0; -- don't print

                case
                    when s1(a).sid = s2(b).sid then

                        case
                            when s1(a).statistic# = s2(b).statistic# then

                                delta := s2(b).value - s1(a).value;
                                evcnt := s2(b).event_count - s1(a).event_count;
                                --output('DEBUG, s1(a).statistic#  s2(b).statistic#, a='||to_char(a)||' b='||to_char(b)||' s1.count='||s1.count||' s2.count='||s2.count||' s2.count='||s2.count);
                                if delta != 0 then fout(); end if;

                                a := a + 1;
                                b := b + 1;

                            when s1(a).statistic# > s2(b).statistic# then

                                delta := s2(b).value;
                                evcnt := s2(b).event_count;
                                if delta != 0 then fout(); end if;

                                b := b + 1;

                            when s1(a).statistic# < s2(b).statistic# then

                                output('ERROR, s1(a).statistic# < s2(b).statistic#, a='||to_char(a)||' b='||to_char(b)||' s1.count='||s1.count||' s2.count='||s2.count||' s2.count='||s2.count);
                                a := a + 1;
                                b := b + 1;

                        else
                                output('ERROR, s1(a).statistic# ? s2(b).statistic#, a='||to_char(a)||' b='||to_char(b)||' s1.count='||s1.count||' s2.count='||s2.count||' s2.count='||s2.count);
                                a := a + 1;
                                b := b + 1;

                        end case; -- s1(a).statistic# ... s2(b).statistic#

                    when s1(a).sid > s2(b).sid then

                        delta := s2(b).value;
                        evcnt := s2(b).event_count;
                        if delta != 0 then fout(); end if;

                        b := b + 1;

                    when s1(a).sid < s2(b).sid then

                        if disappeared_sid != s1(a).sid then
                            output('WARN, Session has disappeared since previous snapshot, ignoring SID='||to_char(s1(a).sid)||' debug(a='||to_char(a)||' b='||to_char(b)||' s1.count='||s1.count||' s2.count='||s2.count||' s2.count='||s2.count||')');
                        end if;
                        disappeared_sid := s1(a).sid;                    
                        a := a + 1;

                    else
                        output('ERROR, Should not be here, SID='||to_char(s2(b).sid)||' a='||to_char(a)||' b='||to_char(b)||' s1.count='||s1.count||' s2.count='||s2.count||' s2.count='||s2.count);

                end case; -- s1(a).sid ... s2(b).sid

                i:=i+1;

                if  delta != 0 then

                    changed_values := changed_values + 1;

                end if; -- delta != 0

            end loop; -- while ( a <= s1.count and b <= s2.count )

            if pagesize > 0 and changed_values > 0 then 
                output(' ');
                output('--  End of Stats snap '||to_char(c)||', end='||to_char(d2, 'YYYY-MM-DD HH24:MI:SS')||', seconds='||round(get_seconds(d2-d1), 1)); 
            end if;

            output(' ');

        end if; -- gather_stats = 1

        if gather_ash = 1 then

            -- get ASH sample grouping details
            g_ash_columns  := nvl( getopt('&snapper_options', 'ash='  ), g_ash_columns  );

            -- optional additional ASH groupings
            g_ash_columns1 := case when getopt('&snapper_options', 'ash1' ) is null then null when getopt('&snapper_options', 'ash1' ) = chr(0) then g_ash_columns1 else getopt('&snapper_options', 'ash1=' ) end;
            g_ash_columns2 := case when getopt('&snapper_options', 'ash2' ) is null then null when getopt('&snapper_options', 'ash2' ) = chr(0) then g_ash_columns2 else getopt('&snapper_options', 'ash2=' ) end;
            g_ash_columns3 := case when getopt('&snapper_options', 'ash3' ) is null then null when getopt('&snapper_options', 'ash3' ) = chr(0) then g_ash_columns3 else getopt('&snapper_options', 'ash3=' ) end;
            g_ash_columns4 := case when getopt('&snapper_options', 'ash4' ) is null then null when getopt('&snapper_options', 'ash4' ) = chr(0) then g_ash_columns4 else getopt('&snapper_options', 'ash4=' ) end;
            g_ash_columns5 := case when getopt('&snapper_options', 'ash5' ) is null then null when getopt('&snapper_options', 'ash5' ) = chr(0) then g_ash_columns5 else getopt('&snapper_options', 'ash5=' ) end;
            g_ash_columns6 := case when getopt('&snapper_options', 'ash6' ) is null then null when getopt('&snapper_options', 'ash6' ) = chr(0) then g_ash_columns6 else getopt('&snapper_options', 'ash6=' ) end;

            -- group ASH records and print report
            out_ash( g_ash_columns, 10 );
            -- group and print optional ASH reports
            if g_ash_columns1 is not null then out_ash( g_ash_columns1, 10 ); end if;
            if g_ash_columns2 is not null then out_ash( g_ash_columns2, 10 ); end if;
            if g_ash_columns3 is not null then out_ash( g_ash_columns3, 10 ); end if;
            if g_ash_columns4 is not null then out_ash( g_ash_columns4, 10 ); end if;
            if g_ash_columns5 is not null then out_ash( g_ash_columns5, 10 ); end if;
            if g_ash_columns6 is not null then out_ash( g_ash_columns6, 10 ); end if;


            if pagesize > 0 then 
                output(' '); 
                output('--  End of ASH snap '||to_char(c)||', end='||to_char(ash_date2, 'YYYY-MM-DD HH24:MI:SS')||', seconds='||to_char(round((ash_date2-ash_date1) * 86400, 1))||', samples_taken='||g_ash_samples_taken||', AAS='||CASE WHEN g_ash_samples_taken = 0 THEN '(No ASH sampling in begin/end snapshot mode)' ELSE TO_CHAR(ROUND(g_ash.COUNT/NULLIF(g_ash_samples_taken,0),1)) END ); 
                --output('--  End of ASH snap '||to_char(c)||', end='||to_char(ash_date2, 'YYYY-MM-DD HH24:MI:SS')||', seconds='||to_char(round((ash_date2-ash_date1) * 86400, 1))||', samples_taken='||g_ash_samples_taken||', AAS='||TO_CHAR(ROUND(g_ash.COUNT/g_ash_samples_taken,1))||', Active%='||TO_CHAR(ROUND(g_ash.COUNT/g_ash_samples_taken*100,1))||'%' ); 

                output(' '); 
            end if;

            reset_ash();

        end if; -- gather_ash = 1

    end loop; -- for c in 1..snapper_count

    exception when others then
        raise_application_error(-20000, 'Snapper: Probably bad syntax or no execute rights on SYS.DBMS_LOCK'||chr(10)||'Check http://blog.tanelpoder.com/snapper for instructions'||chr(10)||sqlerrm);

end;
/

undefine snapper_sleep
undefine snapper_count
undefine snapper_sid
undefine ssid_begin
undefine _IF_ORA12_OR_HIGHER
undefine _IF_ORA11_OR_HIGHER
undefine _IF_LOWER_THAN_ORA11
undefine _IF_LOWER_THAN_ORA12
undefine _NO_BLK_INST
undefine _YES_BLK_INST
undefine _NO_PLSQL_OBJ_ID
undefine _YES_PLSQL_OBJ_ID
undefine _IF_DBMS_SYSTEM_ACCESSIBLE
undefine _IF_X_ACCESSIBLE
undefine _MANUAL_SNAPSHOT
undefine _USE_DBMS_LOCK
col snapper_ora12higher    clear
col snapper_ora12lower     clear
col snapper_ora11higher    clear
col snapper_ora11lower     clear
col dbms_system_accessible clear
col x_accessible           clear 
col no_plsql_obj_id        clear 
col yes_plsql_obj_id       clear 
col no_blk_inst            clear 
col yes_blk_inst           clear 
col manual_snapshot        clear 
col use_dbms_lock          clear 
col snapper_sid            clear 
col sid_filter             clear 
col inst_filter            clear 

set serveroutput off

 



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