Category: SQL

3

What to do with a Character you Cannot Query

This post comes out of one of the more challenging technical problems I have encountered recently. Problem Description An international client went live recently. We did the work of building their new WebSphere Commerce 7 website, and go-live involved loading some data from their old site. I’m not sure exactly how that load was done, but I suspect massload (a...

1

DB2 Basics: Triggers

As with the other entries in my DB2 Basics series, this entry does not cover everything about triggers. Instead, I’m covering the basics and a few important points. DB2 triggers are sometimes over-used and over-complicated. Basically, triggers are actions(SQL) that take place when a triggering action occurs. Triggering Actions For DB2, the valid triggering actions are on a table basis....

7

DB2 Table Scans

What is a table scan? DB2 has a number of ways of accessing the data it needs, but the most basic one – the one that will always work to get what it needs – is the table scan. A Table scan means that DB2 will read through every single row in a table to get the data it needs....

10

10 Minute Triage: Assessing Problems Quickly (Part 2)

(For Part 1 of this series, please click 10 Minute Triage: Assessing Problems Quickly, Part 1). One of my favorite commercials is from a motor oil company. The scene begins with a man who is sleeping soundly. His slumber ends abruptly when he is physically grabbed by the collar, shoved on a treadmill  and forced to run in an all...

16

10 Minute Triage: Assessing Problems Quickly (Part 1)

To eliminate any confusion – I am not Ember. Ember is a little shorter, with a big smile, and glasses. I was lucky enough to meet her through a mutual friend at the IDUG 2012 Conference in Denver just a few weeks ago. After enough networking events and sessions, we found we had similar technical backgrounds and began swapping stories....

1

VARCHAR: Friend or Foe

I read an article from Craig Mullins on “Working with variable data“. The rest of this post is going to assume you’ve read it, so click through and then come back. I’ve seen performance issues caused by VARCHAR before, and Craig makes some interesting points. VARCHARs are actually one of the big reasons to Reorg frequently. His post is geared...

0

More advanced SQL analysis

So the basics of analyzing SQL on db2 are in my post on Analyzing SQL. I wanted to go a bit beyond the basics. First, you have to be able to read an explain plan. A couple of resources on that: http://web.archive.org/web/20040603042937/http://www.idug.org/idug/member/journal/Nov01/articl05.cfm http://www.ibm.com/support/knowledgecenter/SSEPGG_9.7.0/com.ibm.db2.luw.admin.perf.doc/doc/c0005134.html   I’m not doing to describe reading explain plans at this time, but it is absolutely critical...