The Self-Tuning Memory Manager (STMM)

Edited 12/13/2017 to correct image and details about the database heap.

Db2 memory management is a complex topic that I’ve already written about from several perspectives, and have a few blog entries in mind to explore further. A presentation that Melanie Stopfer gave a while back really helped me understand STMM better.… Read the rest

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Reclaimable Table Spaces

In DB2 9.7, IBM changed the format of table spaces to be “reclaimable”. This has a ton of advantages, but conversion is ridiculously painful.

Why Was the Format Changed?

Previously, row addresses (referenced in indexes) were relative to the beginning of the table space.… Read the rest

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Customizing MONREPORT … or not

If you’re not familiar with MONREPORT, see my DB2 Basics entry on MONREPORT first.

Most of the references I’ve seen to customizing the MONREPORT module basically say “get the code out of the database, modify it, and deploy it”. (see IBM DB2 Knowledge Center Entry on Customizing the MONREPORT module reports)

I have found this rather frustrating when I’ve run across it, and when I find a lack of documentation frustrating, I tend to blog to fill the hole as much as possible.… Read the rest

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DB2 Internals: Simple Query Processing

Edited 11/13/2014 to be more specific about coordinator agents.

This is the first in a series of blog entries talking about DB2 internals. I have no intimate knowledge from IBM of how DB2 works internally, just years of watching presentations about the internals and doing my best to understand what DB2 is doing to inform my actions and decisions as a DBA.… Read the rest

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