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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Reducing Contention: Changing Default Isolation Level for Websphere Commerce (WCS)

Krafick

The Problem

I often lean on analogies when I speak to non-technical people about technical topics. For example, I would explain database locking as “two kids fighting for the same candy bar”.  If you introduce isolation levels into the conversation, I would expand the analogy to include “one sibling holding on to a candy bar they care nothing about just because they don’t want the other sibling getting to it”.… Read the rest

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Establishing a DB2 JDBC Connection

KrafickRecently I was forced outside my comfort zone and asked to vet various open source BI tools. I was a report developer in a past life, a database administrator supporting datamarts at various employers, and even supported Cognos backend databases. I thought my past experience gave me an edge when it came to evaluating BI tools.… Read the rest

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Query Performance Analysis

Some of the more complicated work a DBA does is often analyzing a query. Whether it is proactive or in response to a performance problem, there are so many factors that go into query performance. Even when looking at a query that has a performance problem, there is only occasionally a single, obvious cause for all of the problems.… Read the rest

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DB2 Temporary Table Spaces

What is Temp Space in Db2?

Db2 needs some temporary space on disk to perform some actions. Commonly we think of these actions as primarily sort and join operations. These are operations where Db2 will first use the SORTHEAP memory area, but some data sets are just too big to fit in these locations.… Read the rest

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