Author: Ember Crooks

2

Quick Tip: db2look and Triggers

Just a quick tip today. I’ve been dealing quite a lot with triggers lately, and found the -td option on db2look very useful. I hadn’t had cause to use it before, but it has now become part of my default syntax. In my case, I was moving 963 triggers from a development system to production, and db2look without the -td...

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DB2 LUW – What is a Page?

The logical view of a database consists of the standard objects in any RDBMS – Tables, Indexes, etc. There are a number of layers of abstraction between this and the physical hardware level, both in the OS and within DB2. Setting the Page Size The smallest unit of I/O that DB2 can handle is a page. By default, the default...

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Tips on Using db2advis with Multiple Queries

Many times, the SQL analysis I do is extremely focused – mostly on SQL that is a proven resource hog or a suspected problem. Analyzing all SQL used in a particular process can be a bit different, and may not be something that is frequently done in WebSphere Commerce databases. Recently, I had the output of statement event monitors while...

5

Explain Part 3 – Visual Explain

Please start with the first two articles in this series: Explain Part 1 – Explain and the DB2 Optimizer Explain Part 2 – Command Line Explain Plans Using db2exfmt Explain is one of the few areas where I can see the argument for using a GUI. There are some neat features in Visual Explain and I haven’t seen many bugs...

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Happy Third Blogiversary to db2commerce.com!

Wow, I have been blogging for a full three years now! I have only consistently blogged weekly for about 1.5 years. But what success blogging has brought me! I put a lot of effort into my blog. One of my favorite things in the world actually turns out to be writing a good blog post – it can wash away...

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Explain Part 1 – Explain and the DB2 Optimizer

Generating an Explain Plan is easy… Properly reading an Explain Plan is harder… Taking appropriate action is harder still. When I started my career as a physical DBA with IBM Global Services, generating Explain Plans or even general analysis of SQL was not really a part of my job description. As I learned more about performance tuning and the limitiations...

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When is ‘AUTOMATIC’ Not STMM?

Somewhere along the line, I associated ‘AUTOMATIC’ settings for parameters with DB2’s Self-Tuning Memory Manger (STMM). But the two are not associated. Sure, if STMM is set to ON, then some parameters set to AUTOMATIC will be tuned by the STMM, but many parameters can be set to automatic whether STMM is ON or not. What Parameters STMM can Change...