One of the most important areas for tuning DB2 subsystem performance is memory usage. DB2 for z/OS uses memory for buffer pools, the EDM pool, RID pool and sort pools to cache data and structures in memory. The better memory is allocated to these structures, the better DB2 will perform.When allocating DB2 buffer pools, keep these rules of thumb in mind:Don't allocate everything to a single buffer pool (e.g., BP0); use a multiple buffer pool strategy.Explicitly specify a buffer pool for every table space and index. Isolate the DB2 Catalog in BP0;...
Tuesday, 28 April 2009
Thursday, 16 April 2009
Stages 3 and 4
Posted on 11:52 by Unknown
All good DB2 developers and DBAs know about Stage 1 and Stage 2 predicates, right? But have you ever heard of Stage 3 and Stage 4 predicates? Well, you’re about to! First of all, let’s do a quick review to catch those readers who don’t know what Stage 1 and 2 are. You may have heard about sargable and nonsargable, and if so, Stage 1 is sargable and Stage 2 is nonsargable. If not, don’t worry about those terms, they are obsolete.A predicate that can be evaluated in the Data Manager (DM) component of DB2, that is at the earliest stage of query execution,...
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