IBM DB2 - The Ultimate Database for Cloud, Analytics & Mobile
Terry Purcell has not received any gifts yet
By Terry Purcell
When DB2 9 for z/OS delivered plan management, the goal was to allow a backup of your static SQL packages such that you could “switch” back to the prior “good” access path if a new REBIND resulted in regression. Although optional in DB2 9, EXTENDED became the default in DB2 10 for z/OS – which allowed an “original” and a “previous” to be stored. The previous would be replaced each REBIND, but the original – that is populated upon first REBIND when…Continue
I recently wrote about the most common mistakes that are made with respect to RUNSTATS collection in DB2 for z/OS. [[LINK: http://destinationz.org/Mainframe-Solution/Systems-Administration/Make-No-Mistake ]] The responses were positive, but looking into this further, I see that these mistakes are being made more frequently…Continue
The DB2 optimizer exploits the catalog information to choose an access path for a given SQL statement, and RUNSTATS is what populates the catalog. It is important therefore to collect a good base of statistics to give the optimizer a fighting chance of choosing well-performing access paths for your SQL.
Here we will discuss some common mistakes that are made when running RUNSTATS.…Continue