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Focusing Your Oracle Database Tuning Efforts For PeopleSoft Applications

Focusing Your Oracle Database Tuning Efforts For PeopleSoft Applications. Bobby Durrett U. S. Foodservice, Inc. Introduction. PeopleSoft is a complicated application There are many things that can be tuned – hardware, operating system, Oracle and the application

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Focusing Your Oracle Database Tuning Efforts For PeopleSoft Applications

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  1. Focusing Your Oracle Database Tuning Efforts For PeopleSoft Applications Bobby Durrett U. S. Foodservice, Inc.

  2. Introduction • PeopleSoft is a complicated application • There are many things that can be tuned – hardware, operating system, Oracle and the application • There are many books, articles, etc. on Oracle tuning • Need a way to focus your efforts on the one area that will help the most

  3. Oracle Server Processes • Each PeopleSoft program connects to an Oracle server process • If a PeopleSoft program that you care about is slow you need to see where its Oracle process is spending its time • If you can find out where the server process is spending the majority of its time you can focus your tuning efforts on reducing that time

  4. Oracle Server Processes - continued • A reduction in the Oracle server process’s time will result in an equal reduction in the PeopleSoft program’s time • An Oracle server process is a window on all the other pieces of the database - it is where the PeopleSoft application touches everything else on the database server

  5. Performance Profile • Oracle supplies CPU time and wait time for a server process • You can produce a “Performance Profile” of the server process or session • CPU time • Wait time • Elapsed time – end time minus start time • CPU time plus wait time should equal elapsed time – but doesn’t always

  6. Example Of A Performance Profile TIMESOURCE ELAPSED_SECONDS ----------------------------- --------------- REALELAPSED 25 db file scattered read 16.000231 CPU 8.87 db file sequential read 1.286592 SQL*Net message from client .257231 log file sync .043774 direct path write .028848 SQL*Net message to client .000039

  7. Where We Are Going From Here • Simple way to get a profile • Four different categories time can fall under • How to find the correct Oracle session • A more accurate way to get a profile • A tool that gives you a profile of SQL that has occurred in the past • Conclusion and references

  8. How To Get A Performance Profile Using V$ Tables – Before Script • Run script to start monitoring an Oracle session • Get waits from V$SESSION_EVENT • Get CPU from V$SESSTAT • Get current time • Store these in a table

  9. DROP TABLE BEFOREOTHERSESSION; CREATE TABLE BEFOREOTHERSESSION AS SELECT SID,EVENT TIMESOURCE,(TIME_WAITED/100) SECONDS FROM V$SESSION_EVENT WHERE SID=&&MONITORED_SID; INSERT INTO BEFOREOTHERSESSION SELECT SID,'CPU' TIMESOURCE,(VALUE/100) SECONDS FROM V$SESSTAT WHERE SID=&&MONITORED_SID AND STATISTIC#=(SELECT STATISTIC# FROM V$STATNAME WHERE NAME='CPU used by this session'); COMMIT;

  10. INSERT INTO BEFOREOTHERSESSION SELECT SID,'REALELAPSED' TIMESOURCE, (SYSDATE-TO_DATE('01/01/1900','MM/DD/YYYY'))*24*60*60 SECONDS FROM V$SESSION WHERE SID=&&MONITORED_SID; COMMIT;

  11. How To Get A Performance Profile Using V$ Tables – After Script • Run script to stop monitoring a session and to get a performance profile report • Union together times for waits, CPU and current time • Subtract the times stored by the before script • Output the difference in order of most time to least

  12. SELECT AFTER.TIMESOURCE, AFTER.SECONDS-BEFORE.SECONDS ELAPSED_SECONDS FROM (SELECT SID,EVENT TIMESOURCE,(TIME_WAITED/100) SECONDS FROM V$SESSION_EVENT WHERE SID=&&MONITORED_SID UNION SELECT SID,'CPU' TIMESOURCE,(VALUE/100) SECONDS FROM V$SESSTAT WHERE SID=&&MONITORED_SID AND STATISTIC#=(SELECT STATISTIC# FROM V$STATNAME WHERE NAME='CPU used by this session')

  13. UNION SELECT SID,'REALELAPSED' TIMESOURCE, (SYSDATE-TO_DATE('01/01/1900','MM/DD/YYYY'))*24*60*60 SECONDS FROM V$SESSION WHERE SID=&&MONITORED_SID) AFTER, BEFOREOTHERSESSION BEFORE WHERE BEFORE.SID=AFTER.SID AND AFTER.TIMESOURCE=BEFORE.TIMESOURCE ORDER BY ELAPSED_SECONDS DESC; DROP TABLE BEFOREOTHERSESSION;

  14. Four Types of Time – Main Point of the Presentation • Non-Idle waits - waits within the database • Idle waits – waits outside the database • CPU • Unaccounted-for time – real time minus sum of waits and CPU

  15. Non-idle Waits • Ones that you hear most about • Lots of documentation about what these mean • Oracle documentation • Metalink • Books • Articles • Can usually reduce these by changing something in the database

  16. Common Non-Idle Waits • buffer busy waits • db file scattered read • db file sequential read • enqueue • latch free • log file sync

  17. Non-Idle Wait Example TIMESOURCE ELAPSED_SECONDS ----------------------------- --------------- REALELAPSED 32 enqueue 30.8 CPU 0

  18. Non-Idle Wait Example • Enqueue wait comprises almost all of the time • Indicates that the session is hung on a lock • Just find the session that is holding the lock and kill it

  19. Idle Waits • Typically recommended that you ignore these • Not as frequently discussed • Many begin with “SQL*Net” • Can’t fix by changing something in the database

  20. Idle Wait Example TIMESOURCE ELAPSED_SECONDS ----------------------------- --------------- REALELAPSED 37 SQL*Net message from dblink 35.51 SQL*Net message from client 1.19 CPU .48 log file sync .02

  21. Idle Wait Example • Almost all of the time spent waiting for “SQL*Net message from dblink” • This means that the time is spent on a remote database • Need to go to the remote database and find the session there and tune it

  22. CPU • Server process’s CPU time • Means that the database blocks being accessed are in memory

  23. CPU Example TIMESOURCE ELAPSED_SECONDS ----------------------------- --------------- REALELAPSED 39 CPU 35.7 db file sequential read 3.18 SQL*Net message from client 1.2 control file parallel write .01 log file sync .01

  24. CPU Example • Almost all of the time is spent using the CPU • Tune SQL to reduce number of memory accesses • No need to look at I/O system’s performance

  25. Unaccounted-For Time • Least-documented concept in this talk • Difference between real time that elapsed and the sum of all the waits and the CPU • It is time that Oracle’s measurements do not account for • Best examples are CPU queue wait time and time spent waiting on paging

  26. Unaccounted-For Time Example TIMESOURCE ELAPSED_SECONDS --------------------------- --------------- REALELAPSED 144 CPU 45.14 SQL*Net message from client .57 db file sequential read .17 db file scattered read .08 log file sync .03

  27. Unaccounted-For Time Example • The majority of the time (2/3) is not accounted for by the CPU time or waits • Three CPU-intensive SQLs running on my single-processor laptop • Unaccounted-for time is time spent on the CPU queue • Fixed by reducing contention for the CPU

  28. Determining Your Oracle Session • To get a profile you have to figure out which session corresponds to the PeopleSoft program that is slow • This is complicated by the fact that all PeopleSoft programs login as the same Oracle user • Also, some Oracle sessions are shared by multiple PeopleSoft users

  29. Many PeopleSoft Programs Connect To One Oracle Session Or Server Process • Batch • Sqr • Cobol • Crystal • Nvision • Application Engine • Two-tier Windows client

  30. Some PeopleSoft programs share Oracle sessions • PeopleSoft’s application server has several connections to the Oracle database • PeopleSoft programs that use the app server share the app server’s Oracle sessions • Web connections • Three-tier Windows Client

  31. How To Find Your Oracle Session Using V$ Tables • Can use V$SESSION and V$SQLAREA to find the active PeopleSoft SQL statements • Oracle user SYSADM • Can use CLIENT_INFO column of V$SESSION to determine PeopleSoft userid and other information • Need to set parameter EnableDBMonitoring=1 in app server config file to get CLIENT_INFO populated

  32. Query To Find Oracle Session Id SELECT A.SID, A.SERIAL#, TO_CHAR(A.LOGON_TIME,'MM-DD-YYYY HH24:MI:SS') "Logon Time", A.CLIENT_INFO, C.SQL_TEXT FROM V$SESSION A,V$SQLAREA C WHERE A.SQL_ADDRESS=C.ADDRESS (+) AND A.SQL_HASH_VALUE=C.HASH_VALUE (+) AND A.USERNAME = 'SYSADM' AND A.STATUS='ACTIVE' ORDER BY A.STATUS,A.SID,A.SERIAL#;

  33. App Server CLIENT_INFO Example • SMITH,,10.1.2.3,PROD,PSAPPSRV, • PeopleSoft userid • User’s IP address • Database name • Program name

  34. SQR CLIENT_INFO Example • JONES,12904 • PeopleSoft user id • SQR Unix process id

  35. Using Extended SQL Trace And TKPROF To Get A Profile • Term comes from Cary Millsap and Jeff Holt’s book – read it for tons more good information about this • Get Oracle trace with waits – “Extended SQL Trace” • Use TKPROF to produce report with waits • Piece together a profile from the TKPROF output • More accurate than V$ tables – contains wait details • Only works in 9i or higher (TKPROF waits=yes)

  36. Trace And TKPROF Commands • Commands to start and stop trace work from sqlplus • First two arguments are session id and serial number • TKPROF arguments indicate use of waits • Orders SQL by total elapsed time so you see the longest running SQLs first

  37. Using Extended Trace and TKPROF To start trace: execute sys.dbms_system.set_ev(12,23,10046,8,’’); To end trace: execute sys.dbms_system.set_ev(12,23,10046,0,’’); TKPROF command: tkprof tracefile.txt tkprofout.txt waits=yes "sort=(PRSELA,EXEELA,FCHELA)" SYS=NO

  38. Example TKPROF Output • I highlight the numbers that will go on a performance profile in red • Elapsed and CPU time come from the first part of the report • The wait times come from the second part

  39. Sample TKPROF Output With Waits select count(*) from dba_segments call count cpu elapsed disk query current rows ------- ------ -------- ---------- ---------- ---------- --------- Parse 1 0.13 0.25 10 52 0 Execute 1 0.00 0.00 0 0 0 Fetch 2 7.99 30.57 18953 319306 0 ------- ------ -------- ---------- ---------- ---------- ---------- total 4 8.1230.83 18963 319358 0

  40. Sample TKPROF Output With Waits Elapsed times include waiting on following events: Event waited on Times Max. Wait Total Waited ----------------------------- Waited ---------- ------------ SQL*Net message to client 2 0.00 0.00 db file scattered read 1974 0.06 17.14 db file sequential read 3621 0.03 5.25 SQL*Net message from client 2 0.01 0.01 ***************************************************************

  41. TKPROF Output As A Performance Profile TIMESOURCE ELAPSED_SECONDS ----------------------------- --------------- REALELAPSED 30.83 db file scattered read 17.14 CPU 8.12 db file sequential read 5.25 SQL*Net message from client 0.01

  42. Using I3 To Get A Profile Of Something In The Past • I3 is a tool from Veritas • Formerly known as Precise • Stores information you need to get a profile of a SQL statement that occurred in the past • Have to piece together profile from two places

  43. In Oracle Display • What I3 calls “In Oracle” time corresponds to what I call: • Non-idle waits – “I/O Wait” • CPU – “Using CPU” • Unaccounted-for time – “CPU wait” or “Memory wait”

  44. Overall Activity Display • What I3 calls “Overall Activity” time corresponds to what I call: • Idle waits – “Request Wait” • Everything else – bundled together under “In Oracle”

  45. Conclusion • Get a profile of the session that corresponds to the PeopleSoft program that is slow • Include all of the information Oracle gives you in the profile and compare it to the real time that elapses • Use that profile to direct your tuning efforts so you don’t waste time trying everything to improve it

  46. References • Direct Contention Identification Using Oracle's Session Wait Event Views - Craig Shallahamer • Microstate Response-time Performance Profiling - Danisment Gazi Unal • Optimizing Oracle Performance – Cary Millsap and Jeff Holt

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