I have started to put indexes on the most critical tables by analyzing the Access Plan in Explain SQL task of DB2 control center and have optained significant performance improvement in most cases.
But however I have problems when reorganizing,or running runstats on my tables. After these operations,when I run Explain Sql again. The results are even worse than the beginning. I also notice that the access plan never uses my indexes so the timeron values rises up to very high levels.
When and how must I use these there commands (reorgchk,reorg,runstats).Additionally are any performance commands that should be considered?

Thanks a lot.