2004 Presentation Q10

8/3/2019 2004 Presentation Q10

http://slidepdf.com/reader/full/2004-presentation-q10 1/20

Quick Tip #10:

Tuning PL/SQL proceduresusing DBMS_PROFILER

Tim GormanPrincipal - SageLogix, Inc.

Email: [email protected]

www.SageLogix.Com

International Oracle Users GroupLive 2004



Agenda

•Overview of tuning tools in Oracle – Tuning SQL

– SQL Trace

–

TKPROF –Oracle Trace Analyzer

–Hotsos Profiler (www.hotsos.com)

–UB Tools Analyzer (www.ubtools.com)

– Tuning PL/SQL

– DBMS_PROFILER



Overview of performance tuning

• In order to improve anything, you have tomeasure it

– Is it processing?

– If so, what exactly is it doing?

– Is it waiting on something?

– If so, what exactly is it waiting for?

• Performance tuning is not an art, but ascience

– The right tool for the job is the key



Understanding where time is spent

User Web server App server DB Server

SQL*Net

message from

client (wait)

SQL*Net

message from

client (wait)

CPU (service)

CPU (service)

db file

sequential read

(wait)

Wait Event

UserResponse

Time



Measuring time

• Tracing – Tracing is the recording of actions performed by a

program, as they are performed

• Oracle SQL tracing

– Event 10046

– alter session set events „10046 trace name contextforever, level 8‟

– exec dbms_support.start_trace

–

New book “Optimizing Oracle Performance” by CaryMillsap and Jeff Holt (O‟Reilly & Associates, Sep 2003)

– ISBN #059600527X



Summarizing trace data

• Recording every action performed by a programgenerates huge volumes of data to analyze

– Forest and trees

– Look at the trees for diagnosing failures

– Look at the forest to tune performance

• Application profiling

– “C” programs: UNIX “prof”

– Java programs: EJP on http://www.sourceforge.net

– Commercial products from http://www.semdesigns.com

– profilers for Java, C#, C++, C, COBOL, other languages

– TKPROF for SQL trace data

• Profiling is the summarization of trace data

http://www.sourceforge.net/

http://www.semdesigns.com/



http://www.sourceforge.net/



Profiling

• Using the UNIX “prof” utility as anexample:

– Compile a “C” program using the “-p” optionto the “cc” compiler command

– When compiled/linked program is executed,trace information is output to a file specifiedby $PROFDIR environment variable (defaultis “./mon.out”)

–

UNIX “prof” utility then reads trace informationand produces a summarized “profile report”which summarizes:

– Number of calls to functions

–

Amount of time spent in each function



Profiling

• SQL Trace is another example – SQL trace is enabled on a session

– All SQL statements executed in that sessiondump trace information to a “.trc” file in

USER_DUMP_DEST – TKPROF program simply reads information in

the “.trc” file and summarizes it, displaying:

– Execution counts

– CPU and elapsed times

– Number of physical, logical I/O

– Number of rows fetched



What if the problem is not SQL?

• SQL statements perform work in the database

– Summarizing SQL trace info is the best tool fortuning SQL

•What if the performance problem was in: – The network? Operating system? DB instance?

– Database wait events can help

– An application program, such as:

– Java, C#, C++, C, COBOL, Fortran, Lisp?

– PL/SQL?



DBMS_PROFILER

• Introduced with Oracle8i • Not installed with typical installation

– Some files in “$ORACLE_HOME/rdbms/admin”

– Documented in MetaLink note #243755.1

– Download “prof.zip ” from MetaLink

– “Oracle PL/SQL Supplied Packages” reference on“DBMS_PROFILER”

•Generates trace data in PL/SQL programs – Trace data saved to tables in database

– SQL*Plus script produces summarized “profilereport” as HTML



DBMS_PROFILER

• Files found in “$ORACLE_HOME/rdbms/admin” • SQL*Plus script “profload.sql ” creates the package

DBMS_PROFILER

– Run once for global setup on database

–

Must be performed by SYS user – Also validates package after creation

• SQL*Plus script “proftab.sql ” creates tables tostore trace data

– Create private sets of tables for each user

– Each user has the three tables and single sequence

– Create a “global set” of tables for all users

– DBA is responsible for granting appropriatepermissions and creating synonyms for the three

tables and the single sequence



DBMS_PROFILER

• Important extra files provided in “prof.zip ” – SQL*Plus script “profiler.sql ”

– Queries data generated by runs of theDBMS_PROFILER package

– Generates HTML profiler report as output

– SQL*Plus script “profgsrc.sql ”

– Extracts the source of a stored package,

procedure, or function to an ASCII text file forediting

–So that DBMS_PROFILER procedures canbe added to that source code…



Using DBMS_PROFILER

• Initial setup:

– DBMS_PROFILER package has been created bythe DBA using “profload.sql ”…

–

developer/user has created the tables using“proftab.sql ”

• Add profiler procedures to PL/SQL source

– Procedure START_PROFILER(„run-comment ‟)

– Procedure STOP_PROFILER

• Recompile and run the procedure



Using DBMS_PROFILER

• After running an instrumented PL/SQLprogram:

– Execute the SQL*Plus script “profiler.sql ”

– It will display each session‟s RUN-ID, atimestamp, and the RUN-COMMENT

– Choose the appropriate RUN-ID

– Produces spooled output to a file named

“profiler_<RUNID>.html ”



Case Study #1

• A PL/SQL procedure named PROFTEST1 – It queries data from a table

– Stores the data in a comma-separated string

–

Then, repeatedly parses and displays each itemin the string

• There are (at least) two ways to call theINSTR() function:

– instr(string, „,‟, 1, n)

– instr(string, „,‟, x, 1)

– Which is faster??? Is there a difference?



Case Study #1

•Files: – proftest1.sql

– DDL to create stored procedure and table

–Including use of DBMS_PROFILER

– run_proftest1.sql

– SQL*Plus script to run the test

– proftest1.tkp

–

Output from tkprof <trc-file> <tkp-file> sort=prsela,exeela,fchela explain=<un>/<pwd>

– proftest1_18.html

– proftest1_19.html



Case Study #1

• No real surprise when you think about it – But using “instr(string, pattern, m, n)” is faster

– But THAT MUCH FASTER???



Case Study #2

• Script to estimate the number of rows perblock

– Originally written for Oracle v6

–

Adapted to Oracle7 without modification – New ROWID formats in v8+ forced changes to

the script

• Started using DBMS_ROWID package in

query

– Extremely slow



Case Study #2

• DBMS_PROFILER does not affect PL/SQLmodules called within SQL statements

– Unless they are instrumented themselves withSTART/STOP_PROFILER

• The resolution of replacing DBMS_ROWIDpackage calls with SUBSTR was easilydetermined using SQL Trace and TKPROF

– But DBMS_PROFILER provided somecorroboration, at least… :-)



Quick Tip #Q10Q & A

Slides and scripts will be posted onhttp://www.SageLogix.com

andhttp://www.EvDBT.com

Email: [email protected]

http://www.sagelogix.com/

http://www.evdbt.com/

mailto:[email protected]



http://www.evdbt.com/

http://www.sagelogix.com/

Documents

2004 Presentation Q10