We are running db2 8.1 fixpack 10 on AIX 5.2 with MQ 5.3 as our transaction manager.

Our system recently went to 7x24 operation and we have switched over to online maintenance activities. We are noticing a slowdown in processing online transactions. Although the DB2 logs do not report any issues we are wondering if online index reorg or online runstats (allow write access) will do any locking at some point? Even for just a short period of time? And if so could this degrade performance?

Online maintenance operations have to operate on the real data to have any effect. Since other transactions may be going which should usually get correct results when operating on the data, it is mandatory that DB2 synchronizes the data access. So the answer is "yes, online reorg must acquire locks". (I'm not sure if runstats will simply read uncommitted data.)

Yes, runstats uses dirty read to calculate stats. It uses an "intent none" type lock which will only bar "super exclusive" locks.

Andy

thanks guys!