Debugging/Tuning Queries via Debugging/Tuning Queries via iSeries NavigatoriSeries Navigator

Tom McKinleyTom McKinleyMac2@us.ibm.comMac2@us.ibm.com

Tour Tour

What’s info is available What’s info is available – System MonitoringSystem Monitoring– Collection ServicesCollection Services– Work Management Work Management – Table Table – Show IndexesShow Indexes

– Index Advisor (DB, Schema or table level) Index Advisor (DB, Schema or table level) BETA BETA ONLY, removed from presentation. ONLY, removed from presentation.

– Stats Stats

System Level MonitoringSystem Level Monitoring

Example System MonitorExample System Monitor

Open MonitorOpen Monitor

Active JobsActive Jobs

Current SQL For A JobCurrent SQL For A Job

Current SQL for a jobCurrent SQL for a job

Explain from Current SQL Explain from Current SQL

Index Advised Index Advised

Columns Stats on a table Columns Stats on a table

Column Stats DetailsColumn Stats Details

Statistics Requests Statistics Requests

Other sources of InfoOther sources of InfoDB2 for iSeries Web Site DB2 for iSeries Web Site – http://www-03.ibm.com/servers/eserver/iseries/db2/http://www-03.ibm.com/servers/eserver/iseries/db2/

Monitor queries Monitor queries – http://www-03.ibm.com/servers/eserver/iseries/db2/dbmonqrys.htmhttp://www-03.ibm.com/servers/eserver/iseries/db2/dbmonqrys.htm

White papersWhite papers– http://www-03.ibm.com/servers/eserver/iseries/db2/awp.htmlhttp://www-03.ibm.com/servers/eserver/iseries/db2/awp.html

SQL performance and query optimization guide (Info Center)SQL performance and query optimization guide (Info Center)Common, Tech Conferences…Common, Tech Conferences…Query Performance tuning workshopQuery Performance tuning workshop– http://www-03.ibm.com/servers/eserver/iseries/service/igs/http://www-03.ibm.com/servers/eserver/iseries/service/igs/

db2performance.htmldb2performance.html

Summary Summary

Many things affect query plansMany things affect query plansTry to understand the access methodsTry to understand the access methodsLearn the tools Learn the tools Size mattersSize matters– ““Bad Performance does not scale”.Bad Performance does not scale”.

You need to collect info before you make You need to collect info before you make changes to help understand what changed and changes to help understand what changed and the impact of that change.the impact of that change.Don’t only focus on Runtime. Look for resource Don’t only focus on Runtime. Look for resource hogs, or for queries that are run frequentlyhogs, or for queries that are run frequentlyGood indexing strategy in some cases is criticalGood indexing strategy in some cases is critical