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Intro to ASH

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Intro to ASH

  1. 1. ASH – Active Session History Feel the Power Kyle Hailey http://perfvision.com
  2. 2. #.2 Copyright 2006 Kyle Hailey ASH Whole New Paradigm in Technology The Power of ASH lies in Simplifying Performance Tuning  Totally new and exciting methodology  Cheaper, Quicker, Richer and better tasting too
  3. 3. #.3 Copyright 2006 Kyle Hailey Why should you care? Because ASH can Change your life …  10g immediately Accessible  Geeks: Via scripts in SQL (?/rdbms/admin/ashrpt.sql)  Managers : Graphical OEM 10g  Stuck on Oracle 7,8,9 ? … my apologies because 10g rocks, but … no worries, the data is accessible for you too via scripts http://perfvision.com/sash.php
  4. 4. #.4 Copyright 2006 Kyle Hailey ASH uses Sampling New Paradigm  Clear Vision of the future  Use new sampling technology  Lets go of the need to know 100%  Statistical approximation  Cheaper  Richer Multidimensional Data  Much more powerful, identifies  SQL  Sessions  Objects  Machine  User
  5. 5. #.5 Copyright 2006 Kyle Hailey To identify Players before ASH  Sessions  # sessions x (# wait events + statistics)  Example (150 x (800+200) = 150,000 )  SQL  v$sql  Could be 10000s  Takes out latches that compete with other sql executions  Objects  V$segstat 9i+  Could be 1000s of objects Expensive !
  6. 6. #.6 Copyright 2006 Kyle Hailey ASH – Intelligence for the new Millennium  Intelligently Collects Data  It self adjusts for your needs  More activity, more data collected  Less activity, less data collected  Those old methods collected everything  Obfuscated the problem, too many statistics too late  Costly  Too Granular – once an hour ?! Give me a break
  7. 7. ASH Samples Session State TIME?? ?? ?? ?? ?? Sessions change a lot quicker but can get the main picture via sampling by sampling faster Every secondEvery second 10:00:00 10:00:01 10:00:02 10:00:03 10:00:04 10:00:05
  8. 8. #.8 Copyright 2006 Kyle Hailey Sampling is like taking Pictures
  9. 9. #.9 Copyright 2006 Kyle Hailey If happens a lot or for long … we’ll catch it, guaranteed • Long running queries easily foundLong running queries easily found • Short high execution queries found most of the timeShort high execution queries found most of the time • Short low execution queries rarely foundShort low execution queries rarely found Produces a good representation of load on DBProduces a good representation of load on DB
  10. 10. #.10 Copyright 2006 Kyle Hailey Session States IO CPU IdleWait WorkWork LatencyLatency ContentionContention
  11. 11. #.11 Copyright 2006 Kyle Hailey IDLE  Example : SQL*Net Message from Client  10g  9i or below – just have to keep track  Statspack STATS$IDLE_EVENT select name from v$event_name where wait_class='Idle'; 58 Rows
  12. 12. #.12 Copyright 2006 Kyle Hailey CPU  ASH: SESSION_STATE = “ON CPU”  ASH: wait_time > 0 10g: v$session 9i: v$session_wait w.wait_time != 0 /* on CPU */ and s.status='ACTIVE' /* ACTIVE */ Identifying CPU via v$session_wait isIdentifying CPU via v$session_wait is a huge break througha huge break through
  13. 13. #.13 Copyright 2006 Kyle Hailey IO  ASH: SESSION_STATE=‘WAITING’ &  10g: WAIT_CLASS=‘User I/O’  9i:  Look at 10g for ideas  db file sequential read  db file scattered read  db file parallel read  direct path read
  14. 14. #.14 Copyright 2006 Kyle Hailey WAITING  ASH: SESSION_STATE=‘WAITING’  ASH: WAIT_TIME <= 0  WAIT_CLASS 1. Administrative 2. Application 3. Cluster 4. Commit 5. Concurrency 6. Configuration 7. Network 8. Other 9. Scheduler 10. System I/O  800+ WAIT
  15. 15. Session 1 Session 2 Session 3 Session 4 TIME Samples for all users 10:15:00 10:15:01 10:15:02 10:15:03 10:15:04 10:15:05 10:15:06 10:15:07
  16. 16. #.16 Copyright 2006 Kyle Hailey v$active_session_history SESSION_ID NUMBER SESSION_SERIAL# NUMBER USER_ID NUMBER SERVICE_HASH NUMBER SESSION_TYPE VARCHAR2(10) PROGRAM VARCHAR2(64) MODULE VARCHAR2(48) ACTION VARCHAR2(32) CLIENT_ID VARCHAR2(64) EVENT VARCHAR2(64) EVENT_ID NUMBER EVENT# NUMBER SEQ# NUMBER P1 NUMBER P2 NUMBER P3 NUMBER WAIT_TIME NUMBER TIME_WAITED NUMBER CURRENT_OBJ# NUMBER CURRENT_FILE# NUMBER CURRENT_BLOCK# NUMBER0 SQL_ID VARCHAR2(13) SQL_CHILD_NUMBER NUMBER SQL_PLAN_HASH_VALUE NUMBER SQL_OPCODE NUMBER QC_SESSION_ID NUMBER QC_INSTANCE_ID NUMBER SAMPLE_ID NUMBER SAMPLE_TIME TIMESTAMP(3) When Session SQL Wait SESSION_STATE VARCHAR2(7) WAIT_TIME NUMBER State TIME_WAITED NUMBER Duration
  17. 17. #.17 Copyright 2006 Kyle Hailey Groupings – Top Consumer SESSION_ID SESSION_SERIAL# (signal SID reuse) SESSION_TYPE (FOREGROUND,BACKGROUND) CURRENT_OBJ# CURRENT_FILE# CURRENT_BLOCK# USER_ID (SYS, SYSTEM, SCOTT etc) SERVICE_HASH (OE,GL,HR) PROGRAM (SQL, JDBC, Forms etc) MODULE.ACTION(PLSQL tagging) CLIENT_ID (identifying users in a session pool) SQL_ID QC_SESSION_ID - Query Coordinator QC_INSTANCE_ID – RAC EVENT + P1, P2, P3
  18. 18. #.18 Copyright 2006 Kyle Hailey Amazing things YOU can do with ASH Consumers  Top Session  Top User  Top SQL  Top Object  Top Module.Action  Top Program  Top Service  Top Client  Top Wait No machine  - collect on logon trigger X Resources • CPU • Waits • Event (800*) • I/O • File • Block • Time Find top consumers by resource usage
  19. 19. #.19 Copyright 2006 Kyle Hailey Select session_id, count(*) from v$active_session_history where session_state= ‘ON CPU‘ and SAMPLE_TIME > sysdate – (5/(24*60)) group by session_id order by count(*) desc; Select session_id, count(*) from v$active_session_history where session_state= ‘ON CPU‘ and SAMPLE_TIME > sysdate – (5/(24*60)) group by session_id order by count(*) desc; Top CPU Session Who is the rogue session ?
  20. 20. #.20 Copyright 2006 Kyle Hailey Results Top CPU Session SESSION_ID COUNT(*) ---------- ---------- 265 256 264 15 257 12 271 12 276 1 SESSION_ID COUNT(*) ---------- ---------- 265 256 264 15 257 12 271 12 276 1 SESSION_ID COUNT(*) ---------- ---------- 265 256 264 15 257 12 271 12 276 1
  21. 21. #.21 Copyright 2006 Kyle Hailey CPU with Bars SESSION_ID COUNT(*) % Bar ---------- ---------- ---------- ------------ 257 75 25 |*** | 263 62 21 |** | 256 32 11 |* | 264 9 3 | | 277 3 1 | | 258 1 0 | | 280 1 0 | | SESSION_ID COUNT(*) % Bar ---------- ---------- ---------- ------------ 257 75 25 |*** | 263 62 21 |** | 256 32 11 |* | 264 9 3 | | 277 3 1 | | 258 1 0 | | 280 1 0 | | Bar shows 10% incrementsBar shows 10% increments
  22. 22. #.22 Copyright 2006 Kyle Hailey Select session_id, count(*) from v$active_session_history where session_state=‘WAITING’ and SAMPLE_TIME > SYSDATE - (5/(24*60)) group by session_id order by count(*) desc; Select session_id, count(*) from v$active_session_history where session_state=‘WAITING’ and SAMPLE_TIME > SYSDATE - (5/(24*60)) group by session_id order by count(*) desc; Top Waiting Session  Top Waiting Session in last 5 minutes
  23. 23. #.23 Copyright 2006 Kyle Hailey SESSION_ID COUNT(*) ---------- ---------- 272 224 254 8 249 5 276 5 277 4 270 1 SESSION_ID COUNT(*) ---------- ---------- 272 224 254 8 249 5 276 5 277 4 270 1 Top Waiting Session Results
  24. 24. #.24 Copyright 2006 Kyle Hailey Top SQL from ASH select ash.SQL_ID , sum(decode(ash.session_state,'ON CPU',1,0)) "CPU", sum(decode(ash.session_state,'WAITING',1,0)) - sum(decode(ash.session_state,'WAITING', decode(en.wait_class, 'User I/O',1,0),0)) "WAIT" , sum(decode(ash.session_state,'WAITING', decode(en.wait_class, 'User I/O',1,0),0)) "IO" , sum(decode(ash.session_state,'ON CPU',1,1)) "TOTAL" from v$active_session_history ash, v$event_name en where SQL_ID is not NULL and en.event#=ash.event# group by sql_id order by sum(decode(session_state,'ON CPU',1,1)) desc select ash.SQL_ID , sum(decode(ash.session_state,'ON CPU',1,0)) "CPU", sum(decode(ash.session_state,'WAITING',1,0)) - sum(decode(ash.session_state,'WAITING', decode(en.wait_class, 'User I/O',1,0),0)) "WAIT" , sum(decode(ash.session_state,'WAITING', decode(en.wait_class, 'User I/O',1,0),0)) "IO" , sum(decode(ash.session_state,'ON CPU',1,1)) "TOTAL" from v$active_session_history ash, v$event_name en where SQL_ID is not NULL and en.event#=ash.event# group by sql_id order by sum(decode(session_state,'ON CPU',1,1)) desc
  25. 25. #.25 Copyright 2006 Kyle Hailey Top SQL from ASH Results SQL_ID CPU WAITING IO TOTAL ------------- ---------- ---------- ---------- ---------- 4c1xvq9ufwcjc 23386 0 0 23386 6wjw6rz5uvbp3 99 0 23 122 968dm8hr9qd03 97 0 22 119 938jp5gasmrah 90 0 25 115 cv8xnv81kf582 42 0 9 51 6p9bzu19v965k 21 0 0 21 5zu8pxnun66bu 15 0 0 15 db2jr13nup72v 9 0 0 9 7ks5gnj38hghv 8 0 0 8 SQL_ID CPU WAITING IO TOTAL ------------- ---------- ---------- ---------- ---------- 4c1xvq9ufwcjc 23386 0 0 23386 6wjw6rz5uvbp3 99 0 23 122 968dm8hr9qd03 97 0 22 119 938jp5gasmrah 90 0 25 115 cv8xnv81kf582 42 0 9 51 6p9bzu19v965k 21 0 0 21 5zu8pxnun66bu 15 0 0 15 db2jr13nup72v 9 0 0 9 7ks5gnj38hghv 8 0 0 8
  26. 26. #.26 Copyright 2006 Kyle Hailey Top Session select ash.session_id, ash.session_serial#, ash.user_id, ash.program, sum(decode(ash.session_state,'ON CPU',1,0)) "CPU", sum(decode(ash.session_state,'WAITING',1,0)) - sum(decode(ash.session_state,'WAITING', decode(en.wait_class,'User I/O',1, 0 ), 0)) "WAITING" , sum(decode(ash.session_state,'WAITING', decode(en.wait_class,'User I/O',1, 0 ), 0)) "IO" , sum(decode(session_state,'ON CPU',1,1)) "TOTAL" from v$active_session_history ash, v$event_name en where en.event# = ash.event# group by session_id,user_id,session_serial#,program order by sum(decode(session_state,'ON CPU',1,1)) select ash.session_id, ash.session_serial#, ash.user_id, ash.program, sum(decode(ash.session_state,'ON CPU',1,0)) "CPU", sum(decode(ash.session_state,'WAITING',1,0)) - sum(decode(ash.session_state,'WAITING', decode(en.wait_class,'User I/O',1, 0 ), 0)) "WAITING" , sum(decode(ash.session_state,'WAITING', decode(en.wait_class,'User I/O',1, 0 ), 0)) "IO" , sum(decode(session_state,'ON CPU',1,1)) "TOTAL" from v$active_session_history ash, v$event_name en where en.event# = ash.event# group by session_id,user_id,session_serial#,program order by sum(decode(session_state,'ON CPU',1,1)) select ash.session_id, ash.session_serial#, ash.user_id, ash.program, sum(decode(ash.session_state,'ON CPU',1,0)) "CPU", sum(decode(ash.session_state,'WAITING',1,0)) - sum(decode(ash.session_state,'WAITING', decode(en.wait_class,'User I/O',1, 0 ), 0)) "WAITING" , sum(decode(ash.session_state,'WAITING', decode(en.wait_class,'User I/O',1, 0 ), 0)) "IO" , sum(decode(session_state,'ON CPU',1,1)) "TOTAL" from v$active_session_history ash, v$event_name en where en.event# = ash.event# group by session_id,user_id,session_serial#,program order by sum(decode(session_state,'ON CPU',1,1))
  27. 27. #.27 Copyright 2006 Kyle Hailey Top Session Results SESSION_ID SERIAL# USER_ID PROGRAM CPU WAITING IO ---------- ------- ---------- ------------------------- ------- ---------- ---------- 247 61970 1 sqlplus 11698 0 0 277 1 0 oracle@labsfrh903 (LGWR) 14 21 0 276 1 0 oracle@labsfrh903 (CKPT) 19 10 0 278 1 0 oracle@labsfrh903 (DBW0) 29 0 0 280 1 0 oracle@labsfrh903 (PMON) 19 0 0 254 22617 5 Executor.exe 13 0 3 255 12877 5 Executor.exe 11 0 5 257 33729 5 Executor.exe 15 0 1 255 13417 5 Executor.exe 14 0 2 SESSION_ID SERIAL# USER_ID PROGRAM CPU WAITING IO ---------- ------- ---------- ------------------------- ------- ---------- ---------- 247 61970 1 sqlplus 11698 0 0 277 1 0 oracle@labsfrh903 (LGWR) 14 21 0 276 1 0 oracle@labsfrh903 (CKPT) 19 10 0 278 1 0 oracle@labsfrh903 (DBW0) 29 0 0 280 1 0 oracle@labsfrh903 (PMON) 19 0 0 254 22617 5 Executor.exe 13 0 3 255 12877 5 Executor.exe 11 0 5 257 33729 5 Executor.exe 15 0 1 255 13417 5 Executor.exe 14 0 2
  28. 28. #.28 Copyright 2006 Kyle Hailey Top Session w/ Username select decode(nvl(to_char(s.sid),-1),-1,'DISCONNECTED','CONNECTED') "STATUS", topsession.session_id "SESSION_ID", u.name "NAME", topsession.program "PROGRAM", max(topsession.CPU) "CPU", max(topsession.WAITING) "WAITING", max(topsession.IO) "IO", max(topsession.TOTAL) "TOTAL" from ( {previous query} ) topsession, v$session s, user$ u where u.user# =topsession.user_id and /* outer join to v$session because the session might be disconnected */ topsession.session_id = s.sid (+) and topsession.session_serial# = s.serial# (+) group by topsession.session_id, topsession.session_serial#, topsession.user_id, topsession.program, s.username,s.sid,s.paddr,u.name order by max(topsession.TOTAL) desc select decode(nvl(to_char(s.sid),-1),-1,'DISCONNECTED','CONNECTED') "STATUS", topsession.session_id "SESSION_ID", u.name "NAME", topsession.program "PROGRAM", max(topsession.CPU) "CPU", max(topsession.WAITING) "WAITING", max(topsession.IO) "IO", max(topsession.TOTAL) "TOTAL" from ( {previous query} ) topsession, v$session s, user$ u where u.user# =topsession.user_id and /* outer join to v$session because the session might be disconnected */ topsession.session_id = s.sid (+) and topsession.session_serial# = s.serial# (+) group by topsession.session_id, topsession.session_serial#, topsession.user_id, topsession.program, s.username,s.sid,s.paddr,u.name order by max(topsession.TOTAL) desc
  29. 29. #.29 Copyright 2006 Kyle Hailey Top Session Finding a Rogue User STATUS SESSION_ID NAME PROGRAM CPU WAITING IO --------------- ---------- ---------- ------------------------- ----- ---------- ---- CONNECTED 247 CPU_Monger ChMgr304.exe 11704 0 0 CONNECTED 277 SYS oracle@labsfrh903 (LGWR) 14 19 0 CONNECTED 278 SYS oracle@labsfrh903 (DBW0) 29 0 0 CONNECTED 276 SYS oracle@labsfrh903 (CKPT) 18 9 0 CONNECTED 280 SYS oracle@labsfrh903 (PMON) 20 0 0 DISCONNECTED 255 SYSTEM Executor.exe 11 4 5 DISCONNECTED 257 SYSTEM Executor.exe 13 0 3 DISCONNECTED 255 SYSTEM Executor.exe 14 0 2 DISCONNECTED 257 SYSTEM Executor.exe 13 0 3 STATUS SESSION_ID NAME PROGRAM CPU WAITING IO --------------- ---------- ---------- ------------------------- ----- ---------- ---- CONNECTED 247 CPU_Monger ChMgr304.exe 11704 0 0 CONNECTED 277 SYS oracle@labsfrh903 (LGWR) 14 19 0 CONNECTED 278 SYS oracle@labsfrh903 (DBW0) 29 0 0 CONNECTED 276 SYS oracle@labsfrh903 (CKPT) 18 9 0 CONNECTED 280 SYS oracle@labsfrh903 (PMON) 20 0 0 DISCONNECTED 255 SYSTEM Executor.exe 11 4 5 DISCONNECTED 257 SYSTEM Executor.exe 13 0 3 DISCONNECTED 255 SYSTEM Executor.exe 14 0 2 DISCONNECTED 257 SYSTEM Executor.exe 13 0 3
  30. 30. #.30 Copyright 2006 Kyle Hailey Act.sql : DB Detailed AAS @act Analysis Begin Time : 2007-07-24 11:04:48 Analysis End Time : 2007-07-24 11:19:45 Start time, mins ago: 15 Request Duration : 15 Collections : 528 Data Values : 3327 Elapsed Time: 15 mins WAIT_EVENT CNT % Active Ave_Act_Sess -------------------------------------- ---------- ------------ latch free 10 .3 .02 log buffer space 13 .39 .02 buffer busy waits 14 .42 .03 db file scattered read 15 .45 .03 library cache pin 78 2.34 .15 log file sync 213 6.4 .4 ON CPU 726 21.82 1.38 enqueue 855 25.7 1.62 db file sequential read 1399 42.05 2.65 ------------ sum 6.3 @act Analysis Begin Time : 2007-07-24 11:04:48 Analysis End Time : 2007-07-24 11:19:45 Start time, mins ago: 15 Request Duration : 15 Collections : 528 Data Values : 3327 Elapsed Time: 15 mins WAIT_EVENT CNT % Active Ave_Act_Sess -------------------------------------- ---------- ------------ latch free 10 .3 .02 log buffer space 13 .39 .02 buffer busy waits 14 .42 .03 db file scattered read 15 .45 .03 library cache pin 78 2.34 .15 log file sync 213 6.4 .4 ON CPU 726 21.82 1.38 enqueue 855 25.7 1.62 db file sequential read 1399 42.05 2.65 ------------ sum 6.3
  31. 31. #.31 Copyright 2006 Kyle Hailey Aveact.sql : AAS over time @aveact TM NPTS AVEACT GRAPH CPU WAITS ---------------- ------ ------- ---------------------- ---- ----- 06-AUG 13:00:00 270 .33 +- 2 29 59 06-AUG 14:00:00 1040 2.24 ++--------2--- 341 1984 06-AUG 15:00:00 623 6.67 ++++------2---------- 438 3718 06-AUG 16:00:00 1088 2.59 ++--------2---- 335 2486 06-AUG 17:00:00 1104 1.26 ++----- 2 349 1043 06-AUG 18:00:00 1093 1.38 +++---- 2 663 842 06-AUG 19:00:00 1012 1.74 ++------- 2 373 1388 06-AUG 20:00:00 1131 .99 +---- 2 304 820 06-AUG 21:00:00 1111 1.22 ++----- 2 344 1012 06-AUG 22:00:00 1010 1.66 ++------ 2 414 1259 06-AUG 23:00:00 1120 1.08 +---- 2 298 913 07-AUG 00:00:00 1024 .83 +--- 2 273 576 07-AUG 01:00:00 1006 1.74 ++------- 2 319 1428 07-AUG 02:00:00 1090 2.47 ++--------2---- 347 2345 07-AUG 03:00:00 687 6.59 +++-------2---------- 382 4142 07-AUG 04:00:00 1004 1.95 ++++++--- 2 1299 659 07-AUG 05:00:00 1104 3.08 +++++-----2------ 1170 2226 07-AUG 06:00:00 1122 1.91 +++++++-- 2 1582 558 07-AUG 07:00:00 1115 1.06 +++--- 2 559 618 07-AUG 08:00:00 1140 .81 ++-- 2 403 519 07-AUG 09:00:00 1128 .88 ++--- 2 386 601 @aveact TM NPTS AVEACT GRAPH CPU WAITS ---------------- ------ ------- ---------------------- ---- ----- 06-AUG 13:00:00 270 .33 +- 2 29 59 06-AUG 14:00:00 1040 2.24 ++--------2--- 341 1984 06-AUG 15:00:00 623 6.67 ++++------2---------- 438 3718 06-AUG 16:00:00 1088 2.59 ++--------2---- 335 2486 06-AUG 17:00:00 1104 1.26 ++----- 2 349 1043 06-AUG 18:00:00 1093 1.38 +++---- 2 663 842 06-AUG 19:00:00 1012 1.74 ++------- 2 373 1388 06-AUG 20:00:00 1131 .99 +---- 2 304 820 06-AUG 21:00:00 1111 1.22 ++----- 2 344 1012 06-AUG 22:00:00 1010 1.66 ++------ 2 414 1259 06-AUG 23:00:00 1120 1.08 +---- 2 298 913 07-AUG 00:00:00 1024 .83 +--- 2 273 576 07-AUG 01:00:00 1006 1.74 ++------- 2 319 1428 07-AUG 02:00:00 1090 2.47 ++--------2---- 347 2345 07-AUG 03:00:00 687 6.59 +++-------2---------- 382 4142 07-AUG 04:00:00 1004 1.95 ++++++--- 2 1299 659 07-AUG 05:00:00 1104 3.08 +++++-----2------ 1170 2226 07-AUG 06:00:00 1122 1.91 +++++++-- 2 1582 558 07-AUG 07:00:00 1115 1.06 +++--- 2 559 618 07-AUG 08:00:00 1140 .81 ++-- 2 403 519 07-AUG 09:00:00 1128 .88 ++--- 2 386 601
  32. 32. #.32 Copyright 2006 Kyle Hailey Aveact.sql
  33. 33. #.33 Copyright 2006 Kyle Hailey ““-” = WAIT-” = WAIT ““+” = CPU+” = CPU which waits ? -> aveactn.sqlwhich waits ? -> aveactn.sql
  34. 34. #.34 Aveactn.sql Copyright 2006 Kyle Hailey
  35. 35. #.35 Copyright 2006 Kyle Hailey Many Ways to Attack Problems Confusing  How to Attack the problem?  Top SQL?  Top wait for that SQL?  Top Waiting Session ?  Top Waits for that Session  Top Waits for Database?  Top Session waiting for that wait  Top SQL for that wait Solution - Graphics
  36. 36. #.36 Copyright 2006 Kyle Hailey Mining Data is Non Trivial  Many Dimensions to consider  Constantly Varying time frames  Luckily 10g automates all of this functionality.  collects all of the data  analyses all the wait events  reports on bottlenecks  supplies solutions  Graphics add tremendous ease and power
  37. 37. Session 1 Session 2 Session 3 Session 4 TIME Graphical ASH
  38. 38. #.38 Copyright 2006 Kyle Hailey Graph of User States
  39. 39. #.39 Copyright 2006 Kyle Hailey One Second Graph
  40. 40. #.40 Copyright 2006 Kyle Hailey 15 Second Averages
  41. 41. #.41 Copyright 2006 Kyle Hailey Maximum CPU Line
  42. 42. #.42 Copyright 2006 Kyle Hailey Idle Users
  43. 43. #.43 Copyright 2006 Kyle Hailey OEM Perf Page
  44. 44. #.44 Copyright 2006 Kyle Hailey OEM Perf Page
  45. 45. #.45 Copyright 2006 Kyle Hailey ASH vs Statistics  Statistics  are more expensive  have lag time  lack clear identification of culprits
  46. 46. #.46 Copyright 2006 Kyle Hailey Statistic Lag Time CountersCounters SamplesSamples Slight LagsSlight Lags
  47. 47. #.47 Copyright 2006 Kyle Hailey CPU Lag Problem  ASH is the only way to see CPU usage realtime  V$sysstat reports CPU but  is only updated at the end of the call.  Long calls look deceiving like no CPU is being used
  48. 48. #.48 Copyright 2006 Kyle Hailey CPU in ASH vs Stats
  49. 49. #.49 Copyright 2006 Kyle Hailey ASH Sampling Cheap Three Methods 1.With PL/SQL it’s less that 1 % CPU with 10 average active sessions 2.DMA - direct memory attach to SGA Using C code 200x Cheaper 3.ASH in 10g should be even cheaper than DMA because it’s done in the kernel
  50. 50. #.50 Copyright 2006 Kyle Hailey ASH – In Memory  Collects active session data only  History v$session_wait + v$session + extras  Circular Buffer - 1M to 128M (~2% of SGA)  Flushed every hour to disk or when buffer 2/3 full (it protects itself so you can relax)
  51. 51. #.51 Copyright 2006 Kyle Hailey ASH Sizing …  Avg row around 150bytes  3600 secs in an hour  ~ ½ Meg per Active Session per hour  That’s generally over an hour of ASH
  52. 52. #.52 Copyright 2006 Kyle Hailey How ASH works V$session_wait + v$session + extras MMON/ MMNL v$active_session_history wrh$_active_session_history Only writes out 1 in 10 rows via direct path inserts
  53. 53. #.53 Copyright 2006 Kyle Hailey Select reads backwards -No latching -No read consistency -Index on time Insert point ASH buffer Insert one direction - Touch up wait times
  54. 54. #.54 Copyright 2006 Kyle Hailey Family of ASH Tables v$session_wait v$active_session_history wrh$active_session_history V$session_wait_history DBA_HIST_ACTIVE_SESS_HISTORY
  55. 55. #.55 Copyright 2006 Kyle Hailey ASH Tables v$session_wait SID SEQ# EVENT P1TEXT P1 P1RAW P2TEXT P2 P2RAW P3TEXT P3 P3RAW WAIT_CLASS_ID WAIT_CLASS# WAIT_CLASS WAIT_TIME SECONDS_IN_WAIT STATE v$session_wait_history SID SEQ# EVENT# EVENT P1TEXT P1 P2TEXT P2 P3TEXT P3 WAIT_TIME v$event_name EVENT_ID EVENT# EVENT_ID NAME PARAMETER1 PARAMETER2 PARAMETER3 WAIT_CLASS_ID WAIT_CLASS# WAIT_CLASS v$active_session_history SAMPLE_ID SAMPLE_TIME SESSION_ID SESSION_SERIAL# USER_ID SQL_ID SQL_CHILD_NUMBER SQL_PLAN_HASH_VALUE SQL_OPCODE SERVICE_HASH SESSION_TYPE SESSION_STATE QC_SESSION_ID QC_INSTANCE_ID SEQ# EVENT# P1 P2 P3 WAIT_TIME TIME_WAITED CURRENT_OBJ# CURRENT_FILE# CURRENT_BLOCK# PROGRAM MODULE ACTION CLIENT_ID current 10 samples hour DBA_HIST_ACTIVE_SESS_HISTORY wrh$active_session_history SNAP_D DBID INSTANCE_NUMBER SAMPLE_ID SAMPLE_TIME SESSION_ID SESSION_SERIAL# USER_ID SQL_ID SQL_CHILD_NUMBER SQL_PLAN_HASH_VALUE SQL_OPCODE SERVICE_HASH SESSION_TYPE SESSION_STATE QC_SESSION_ID QC_INSTANCE_ID SEQ# EVENT_ID P1 P2 P3 WAIT_TIME TIME_WAITED CURRENT_OBJ# CURRENT_FILE# CURRENT_BLOCK# PROGRAM MODULE ACTION CLIENT_ID 7 days (disk) 1 in 10
  56. 56. #.56 Copyright 2006 Kyle Hailey Wait Time vs Time Waited  SESSION_STATE  Waiting, on CPU  Based on WAIT_TIME  WAIT_TIME (v$session, v$session_wait, v$ash)  0 => waiting  >0 => CPU (value is time of last wait)  TIME_WAITED  Actual time waited for event  0 until wait finishes  Fix up values (no one else can do this)
  57. 57. #.57 Copyright 2006 Kyle Hailey Oradebug  Dump to trace file SQL> oradebug dump ash 5 SQL> Alter session set events ‘immediate tracename ashdump level 5’; level 5 = # of minutes loader file rdbms/demo/ashldr.ctl SQL> oradebug dump ashdump 5 SQL> Alter session set events ‘immediate tracename ashdump level 5’;
  58. 58. #.58 Copyright 2006 Kyle Hailey INIT.ORA statistics_level = Typical (default) PARAMETER SESSION_VALUE INSTANCE_VAL ----------------------- ---------- ------------ _ash_sampling_interval 1000 1000 milliseconds _ash_size 1048618 1048618 ASH buffer size _ash_enable TRUE TRUE Turn on/off ASH sampling, flushing and the V$ views on ASH _ash_disk_write_enable TRUE TRUE Flush to disk _ash_disk_filter_ratio 10 10 write 1 in 10 points _ash_sample_all FALSE FALSE Sample including idle waits
  59. 59. #.59 10.2 ASH Extras  BLOCKING_SESSION  BLOCKING_SESSION_STATUS  BLOCKING_SESSION_SERIAL#  P1TEXT  P2TEXT  P3TEXT  WAIT_CLASS  WAIT_CLASS_ID  XID  FORCE_MATCHING_SIGNATURE 5901/30/15
  60. 60. #.60 Copyright 2006 Kyle Hailey 10.2 Extras  10gR2 add fields to ASH  Blocking Session Id, serial# and state ***  XID, transaction ID  RAC event Fixup  Plan Hash Fix up  10gR1 - during parsing no plan, good way to find parsing problems  10gR2 – get plan hash fixup – good but lose some ability to find parsing problems  Wait Class, needed this for grouping  Force_matching_signature – sql profile id
  61. 61. #.61 10.2.0.3 ASH Extras PLSQL_ENTRY_OBJECT_ID PLSQL_ENTRY_SUBPROGRAM_ID PLSQL_OBJECT_ID PLSQL_SUBPROGRAM_ID 6101/30/15 ALL_PROCEDURESALL_PROCEDURES where object_id = plsql_object_idwhere object_id = plsql_object_id and subprogram_id = plsql_subprogram_idand subprogram_id = plsql_subprogram_id
  62. 62. #.62 6201/30/15 PLSQL Tracking Package/Procedure/SQL tracking 10.2.0.3 calling_code SQL_ID COUNT(*) ----------------------------------------------- ---------- ORDERENTRY.NEWORDER 0uuqgjq7k12nf 258 ORDERENTRY.NEWCUSTOMER 0bzhqhhj9mpaa 262 ORDERENTRY.BROWSEANDUPDATEORDERS 41zu158rqf4kf 301 ORDERENTRY.NEWORDER 0yas01u2p9ch4 569 PARSE_SAME 3vjxpmhhzngu4 874 ORDERENTRY.BROWSEANDUPDATEORDERS 05s4vdwsf5802 1669 select object_name package||.|| procedure_name, sql_id, count(*) from v$active_session_history ash, all_procedures procs where ash.PLSQL_ENTRY_OBJECT_ID = procs.object_id and ash.PLSQL_ENTRY_SUBPROGRAM_ID = procs.SUBPROGRAM_ID
  63. 63. #.63 Copyright 2006 Kyle Hailey 11g ASH extras SQL ElapsedSQL Elapsed SQL_EXEC_ID SQL_EXEC_START IN_CONNECTION_MGMT IN_PARSE IN_HARD_PARSE IN_SQL_EXECUTION IN_PLSQL_EXECUTION IN_PLSQL_RPC IN_PLSQL_COMPILATION IN_JAVA_EXECUTION IN_BIND IN_CURSOR_CLOSE SQL_PLAN_LINE_ID SQL_PLAN_OPERATION SQL_PLAN_OPTIONS CURRENT_ROW# EVENT# QC_SESSION_SERIAL# CONSUMER_GROUP_ID FLAGS ETCETC CPU Analysis – non TimedCPU Analysis – non Timed SQL Row SourceSQL Row Source REMOTE_INSTANCE# RAC – remote transfersRAC – remote transfers TOP_LEVEL_SQL_ID TOP_LEVEL_SQL_OPCODE Recursive SQLRecursive SQL
  64. 64. #.64 Copyright 2006 Kyle Hailey 11g ASH extras Run-time SQL row source information  Identifies current row source within plan SQL execution ID  Is this same execution as last sample?  can see how long sql has been running Operation bit vector  Capture non-timed operations  Examples: fetch, binding, close Remote instance id for Cache transfers  Which instance sourced requested block?
  65. 65. #.65 Copyright 2006 Kyle Hailey How Many Active Sessions?  How much data does ASH Collect ?  1 CPU means max 1 Avg Active Session unless there is a bottleneck Big site examples:  Oracle 4 way RAC internal apps  10,000 connected, 200 active  One Site  3000 connected, 30 Active  Site  12,000 connected, 100 active
  66. 66. #.66 Copyright 2006 Kyle Hailey Simulating ASH  ASH is new in 10g  ASH data exist since V7  Need Diagnostic Pack License   Collect it yourself   SASH – Simulated ASH http://perfvision.com/sash.php  Graphical Monitor http://perfvision.com/ashmon.php Consumes < 1% CPU for 10 active sessions (a lot)
  67. 67. #.67 Copyright 2006 Kyle Hailey Sampling  Sampling is the future  Took clean vision to create  Bit of a leap of faith  Less Accurate but more powerful than past  Inaccuracies unimportant for the most part  Feasible since version 7  You can implement it yourself  Graphics are the only way to full harness the power
  68. 68. #.68 Copyright 2006 Kyle Hailey Summary  To solve hard problems you need Sampling  If you have 10g and a license you can use  V$active_session_history  OEM 10g (can access some 9 sampling)  ?/rdbms/admim/ashrpt.sql  If you are on 7,8,9 or 10g without the license  Need custom sampling  SASH – Simulated ASH http://perfvision.com/ash.php  ASHMON – graphical http://perfvision.com/ashmon.php
  69. 69. #.69 Copyright 2006 Kyle Hailey ASH Summary Faster, Cheaper, instant (no lag) … but most importantly Rich & Multidimensional  Overview of system load  Drilldowns into problems  Sql  Session  Wait event  Details information on problem resolution  OEM simplifies mining of ASH data

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