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

• 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;

Enabling the SQL Trace Facility

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

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';

Instance wide Tracing

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 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)

tkprof Usage

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.php• 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