Enable 10046 Tracing for a specific SQL

Available methods to enable 10046 trace are described in My Oracle Support Note 376442.1. You can enable 10046-tracing

– on session level (alter session)
– for other sessions (e.g. with oradebug, the package DBMS_MONITOR or DBMS_SYSTEM)

What is not covered with the methods above is the possibility to trace a specific SQL-statement, which runs “somewhen” in the future on the database. E.g. a SQL, which runs during a next batch job. With the introduction of UTS (Unified Tracing Service) in 11.2., you can actually do exactly that:

I.e. suppose I need a 10046-trace, level 12 of the SQL with SQL_ID cjrha4bzuupzf, which runs somewhen in the next 24 hours. So what I have to do is to just set the event “sql_trace” for the SQL_ID:


SQL> alter system set events 'sql_trace[sql: cjrha4bzuupzf] level=12';


REMARK: With the introduction of the parameter “_evt_system_event_propagation” in 11g (default is TRUE) the event-settings of “alter system set events”-commands are also propagated to existing sessions.

Let’s see if only the statement in question is being traced. From another session I’m doing the following:
REMARK: I actually want to trace the statement with the GATHER_PLAN_STATISTICS-hint.


SQL> select /* BEFORE TRACE */ count(*) from t1 where object_type='INDEX';
 
COUNT(*)
----------
1432
 
SQL> select /*+ GATHER_PLAN_STATISTICS */ count(*) from t1 where object_type='INDEX';
 
COUNT(*)
----------
1432
 
SQL> select /*+ AFTER TRACE */ count(*) from t1 where object_type='INDEX';
 
COUNT(*)
----------
1432
 
SQL> select value from v$diag_info where name = 'Default Trace File';
 
VALUE
--------------------------------------------------------------------
D:\APP\CBL\diag\rdbms\gen11204\gen11204\trace\gen11204_ora_11552.trc


Below is the content of the produced trace file:


=====================
PARSING IN CURSOR #305977200 len=79 dep=0 uid=42 oct=3 lid=42 tim=628480230944 hv=4289550318 ad='7ff95ed9ed80' sqlid='cjrha4bzuupzf'
select /*+ GATHER_PLAN_STATISTICS */ count(*) from t1 where object_type='INDEX'
END OF STMT
EXEC #305977200:c=0,e=22,p=0,cr=0,cu=0,mis=0,r=0,dep=0,og=1,plh=3724264953,tim=628480230943
WAIT #305977200: nam='SQL*Net message to client' ela= 1 driver id=1111838976 #bytes=1 p3=0 obj#=15671 tim=628480231942
FETCH #305977200:c=0,e=652,p=0,cr=189,cu=0,mis=0,r=1,dep=0,og=1,plh=3724264953,tim=628480232614
STAT #305977200 id=1 cnt=1 pid=0 pos=1 obj=0 op='SORT AGGREGATE (cr=189 pr=0 pw=0 time=652 us)'
STAT #305977200 id=2 cnt=1432 pid=1 pos=1 obj=15671 op='TABLE ACCESS FULL T1 (cr=189 pr=0 pw=0 time=622 us cost=56 size=10024 card=1432)'
FETCH #305977200:c=0,e=1,p=0,cr=0,cu=0,mis=0,r=0,dep=0,og=0,plh=3724264953,tim=628480232838
WAIT #305977200: nam='SQL*Net message to client' ela= 1 driver id=1111838976 #bytes=1 p3=0 obj#=15671 tim=628480232858
*** 2016-02-05 15:11:21.578
WAIT #305977200: nam='SQL*Net message from client' ela= 1336677 driver id=1111838976 #bytes=1 p3=0 obj#=15671 tim=628481569546
CLOSE #305977200:c=0,e=8,dep=0,type=0,tim=628481569645


So, as expected, only the SQL with SQL_ID cjrha4bzuupzf has been traced.

The event settings done with “alter system set events …” are not persistent settings. I.e. after a next restart of the instance the event is no longer active. To set the event persistently you would have to set it in the spfile as well:


SQL> alter system set event='sql_trace[sql: cjrha4bzuupzf] level=12' scope=spfile;


If you want to see if an event is currently active on the running instance do the following:


SQL> oradebug setmypid
Statement processed.
SQL> oradebug eventdump session
sql_trace[sql: cjrha4bzuupzf] level=12


If you have several events set in your spfile then it’s difficult to remove a single one of them, because the events are stored concatenated with a “:” as a single event. You can just overwrite the current setting or remove them all:


SQL> alter system reset event scope=spfile;


REMARK: Do not set events (except event 10046) without the instruction from Oracle Support to do so. I also do recommend to NOT set event 10046 in the spfile.

Cet article Enable 10046 Tracing for a specific SQL est apparu en premier sur Blog dbi services.