Oracle Tracing
By Shaji

Agenda for the Session
• General Oracle Tracing
• 10,046 Tracing
• Trace Analyzer

Rules of Session:
Interrupt me:
• if you think I have got something wrong.
• if you have a question.
• if you can’t hear me.

Purpose of Tracing
• Measure timing statistics for a given query,
a batch process, or an entire system.
• fast method of finding where potential
bottlenecks on the system reside.

Key Parameters Affecting Tracing:
• TIMED_STATISTICS
Default Value : True
• MAX_DUMP_FILE_SIZE
Default Value : 500 OS Blocks
• USER_DUMP_DEST
Default Value : Operating system-dependent

Enabling the SQL Trace Facility
• DBMS_MONITOR.DATABASE_TRACE_ENABLE
procedure (recommended)
eg:
EXECUTE DBMS_MONITOR.SESSION_TRACE_ENABLE
(session_id => 27, serial_num => 60,waits => TRUE,
binds => FALSE);
EXECUTE DBMS_MONITOR.SESSION_TRACE_DISABLE(
session_id => 27, serial_num => 60);
* Requires DBA Role

Enabling the SQL Trace Facility
• DBMS_SESSION.SET_SQL_TRACE procedure
eg:
EXECUTE DBMS_SESSION.SESSION_TRACE_ENABLE
(waits => TRUE, binds => FALSE);
EXECUTE DBMS_SESSION.SESSION_TRACE_DISABLE();

Enabling the SQL Trace Facility
ALTER SESSION SET SQL_TRACE = TRUE;
SET AUTOTRACE ON;

10,046 Trace
alter session set tracefile_identifier='10046';
alter session set timed_statistics = true;
alter session set statistics_level=all;
alter session set max_dump_file_size = unlimited;
alter session set events '10046 trace name context
forever,level 12';
• -- Execute the queries or operations to be traced here
select * from dual;
exit;
If the session is not exited then the trace can be
disabled using:
alter session set events '10046 trace name context off';

Tracing a process after it has started
Identify the session to be traced
select p.PID,p.SPID,s.SID from v$process p,v$session s
where s.paddr = p.addr and s.sid = &SESSION_ID
/
SPID is the operating system Process identifier (os pid)
PID is the Oracle Process identifier (ora pid)
Login to SQL*Plus as a dba and execute the following:
connect / as sysdba
oradebug setospid “ospid from above query”
oradebug unlimit
oradebug event 10046 trace name context forever,level 12

Tracing a process after it has started
If PID (Oracle Process identifier ) would be used (rather than the 'SPID')
and the oradebug text would change to:
connect / as sysdba
oradebug setorapid 9834
oradebug unlimit
oradebug event 10046 trace name context forever,level 12
To disable oradebug tracing once tracing is finished:
oradebug event 10046 trace name context off

Instance wide Tracing
DBMS_MONITOR:
• EXECUTE DBMS_MONITOR.DATABASE_TRACE_ENABLE(waits => TRUE,
binds => FALSE, instance_name => 'inst1');
• EXECUTE DBMS_MONITOR.DATABASE_TRACE_DISABLE(instance_name
=> 'inst1');
• EXECUTE DBMS_MONITOR.DATABASE_TRACE_DISABLE();
alter system set events '10046 trace name context
forever,level 12';
alter system set events '10046 trace name context off';

Tracing using Logon Trigger
Trace Activity of a Specific User:
CREATE OR REPLACE TRIGGER SYS.set_trace
AFTER LOGON ON DATABASE
WHEN (USER like '&USERNAME')
DECLARE
lcommand varchar(200);
BEGIN
EXECUTE IMMEDIATE 'alter session set statistics_level=ALL';
EXECUTE IMMEDIATE 'alter session set
max_dump_file_size=UNLIMITED';
EXECUTE IMMEDIATE 'alter session set events ''10046 trace name
context forever, level 12''';
END set_trace;
/

Tracing Individual SQL Statements
• SQL trace can be initiated for an individual SQL statement
by substituting the required SQL_ID into the following
statement.
ALTER SESSION SET EVENTS
'trace[rdbms.SQL_Optimizer.*][sql:sql_id]';
ALTER SESSION SET EVENTS
'trace[rdbms.SQL_Optimizer.*] off';
• The SQL_ID of a statement can be found in the V$SQL or
V$SQLSTAT view for recent SQL, or from the
DBA_HIST_SQLSTAT view from the AWR repository for
historical statements.

Where are my trace Files ???
• ALTER SESSION SET TRACEFILE_IDENTIFIER =
"MY_TEST_SESSION";
To find all trace files for the current Session:
• SELECT VALUE FROM V$DIAG_INFO WHERE NAME = 'Default
Trace File';
• To find all trace files for the current instance:
• SELECT VALUE FROM V$DIAG_INFO WHERE NAME = 'Diag
Trace';

Where are my trace Files ???
To determine the trace file for each Oracle Database process:
• SELECT PID, PROGRAM, TRACEFILE FROM V$PROCESS;

Trcsess
• TRCSESS is the tool offered from Oracle to consolidate
trace files. This is needed on shared server installations as
sessions are executed from different processes writing the
sql trace to different log files.
• Consolidates trace output based on Session ID, Client ID,
Service name, Action name, Module name
• After trcsess merges the trace information into a single
output file, the output file could be processed by TKPROF.
trcsess [output=output_file_name]
[session=session_id]
[clientid=client_id]
[service=service_name]
[action=action_name]
[module=module_name]
[trace_files]

where:
• output specifies the file where the output is generated. When
this option is not specified, the standard output is used for the
output.
• session consolidates the trace information for the session
specified. The session Id is a combination of session index and
session serial number.
• clientid consolidates the trace information given client Id.
• service consolidates the trace information for the given service
name.
• action consolidates the trace information for the given action
name.
• module consolidates the trace information for the given module
name.
• trace_files is a list of all trace file names, separated by spaces, in
which trcsess will look for trace information. The wild card
character * can be used to specify the trace file names. If trace
files are not specified, all the files in the current directory are
checked by trcsess.

Trcsess Usage
 In this example the session index and serial number is
equal to 21.2371 & All files in current directory are taken as
input
trcsess session=21.2371
 In this case, several trace files are specified
trcsess session=21.2371 main_12359.trc main_12995.trc

tkprof
• SQL traces files are produced in raw form.
• tkprof utility can be used to translate it to more Human
Readable form
• Tkprof does not control the contents of a trace file, it simply
formats them
Usage: tkprof tracefile outputfile [explain= ] [table= ]
[print= ] [insert= ] [sys= ] [sort= ]

Where
• Filename1  Specifies the input file, a trace file containing statistics
produced by the SQL Trace facility.
• Filename2  Specifies the file to which TKPROF writes its formatted output.
• WAITS  Specifies whether to record summary for any wait events found in
the trace file. Values are YES or NO. The default is YES.
• SORTS  Sorts traced SQL statements in descending order of specified sort
option before listing them into the output file. If more than one option is
specified, then the output is sorted in descending order by the sum of the
values specified in the sort options. If you omit this parameter, then TKPROF
lists statements into the output file in order of first use. Sort options are listed
as follows:
• PRSCNT  Number of times parsed.
• PRSCPU  CPU time spent parsing.
• PRSELA Elapsed time spent parsing.
• PRSDSK  Number of physical reads from disk during parse.

• PRSQRY  Number of consistent mode block reads during parse.
• PRSCU  Number of current mode block reads during parse.
• PRSMIS  Number of library cache misses during parse.
• EXECNT  Number of executes.
• EXECPU  CPU time spent executing.
• EXEELA  Elapsed time spent executing.
• EXEDSK  Number of physical reads from disk during execute.
• EXEQRY  Number of consistent mode block reads during execute.
• EXECU  Number of current mode block reads during execute.
• EXEROW  Number of rows processed during execute.
• EXEMIS  Number of library cache misses during execute.
• FCHCNT  Number of fetches.
• FCHCPU  CPU time spent fetching.
• FCHELA  Elapsed time spent fetching.
• FCHDSK  Number of physical reads from disk during fetch.
• FCHQRY  Number of consistent mode block reads during fetch.
• FCHCU  Number of current mode block reads during fetch.
• FCHROW  Number of rows fetched.
• USERID  Userid of user that parsed the cursor.

• PRINT  Lists only the first integer sorted SQL statements from the output
file. If you omit this parameter, then TKPROF lists all traced SQL statements.
• AGGREGATE  If you specify AGGREGATE = NO, then TKPROF does not
aggregate multiple users of the same SQL text.
• INSERT  Creates a SQL script that stores the trace file statistics in the
database. TKPROF creates this script with the name filename3. This script
creates a table and inserts a row of statistics for each traced SQL statement
into the table.
• SYS  Enables and disables the listing of SQL statements issued by the
user SYS, or recursive SQL statements, into the output file
• TABLE  Specifies the schema and name of the table into which TKPROF
temporarily places execution plans before writing them to the output file.
• EXPLAIN  Determines the execution plan for each SQL statement in the
trace file and writes these execution plans to the output file.
• RECORD  Creates a SQL script with the specified filename4 with all of the
nonrecursive SQL in the trace file. This can be used to replay the user events
from the trace file.
• WIDTH  An integer that controls the output line width of some TKPROF
output, such as the explain plan. This parameter is useful for post-processing
of TKPROF output.

tkprof Usage
• tkprof orcl102_ora_3064.trc output.prf EXPLAIN=scott/tiger
SYS=NO
• TKPROF dlsun12_jane_fg_sqlplus_007.trc OUTPUTA.PRF
EXPLAIN=scott/tiger TABLE=scott.temp_plan_table_a
INSERT=STOREA.SQL SYS=NO SORT=(EXECPU,FCHCPU)

Trace analyzer
• Trace Analyzer, also known as TRCANLZR or TRCA, is a
tool provided by Oracle Server Technologies Center of
Expertise - ST CoE. TRCA inputs one or several SQL
trace(s) generated by Event 10046 and outputs a
diagnostics report in two formats (html and text). These
reports are commonly used to diagnose processes
performing poorly.
• TRCA identifies expensive SQL out of the provided trace(s),
then it connects to the database and collects their explain
plans, Cost-based Optimizer CBO statistics, metadata,
configuration parameters, and similar elements that
influence the performance of the process being analyzed.

Trace analyzer Output
• TRCANLZR (TRCA): SQL_TRACE/Event 10046 Trace
File Analyzer - Tool for Interpreting Raw SQL Traces [ID
224270.1]
HTML Document

Questions

Reference
• Oracle® Database Administrator's Guide 11g Release 1 (11.1) -
chapter 21 Using Application Tracing Tools
• How To Collect 10046 Trace (SQL_TRACE) Diagnostics for
Performance Issues [ID 376442.1]
• http://www.oracle-base.com/articles/misc/sql-trace-10046-trcsess-and-tkprof.• http://docs.oracle.com/cd/B19306_01/appdev.102/b14258/d_monitor.htm
• TRCANLZR (TRCA): SQL_TRACE/Event 10046 Trace File
Analyzer - Tool for Interpreting Raw SQL Traces [ID 224270.1]

Thank You
Shaji- EDMS Team