Category: Troubleshooting

4

DB2 Basics: db2top

There are a lot of things I can cover on db2top, and probably more tips and tricks using db2top than many other tools out there. Searching the web on db2top gets more good results than on many other db2 topics. I thought I’d start with some of the basics. Using db2top requires some general knowledge of how db2 works. I...

3

DB2 Error Logging

(Edited 8/12/2014 to add links to the old tutorials from IBM) There are a number of ways to cover error logging. I have covered some specific elements in previous posts, so I’m going for a more comprehensive approach in this post. There used to be this great “Problem Determination Mastery” certification available. The study material and the test were only...

3

Bad Message Queue Handler. Sit. Stay.

There’s an error message that appears in my db2 diagnostic logs rather frequently. It looks like this: 2014-07-30-13.34.58.446316+000 E1638372A476 LEVEL: Error (OS) PID : 32374944 TID : 1 PROC : db2 INSTANCE: db2inst1 NODE : 000 HOSTNAME: redacted EDUID : 1 FUNCTION: DB2 UDB, oper system services, sqlodque, probe:2 MESSAGE : ZRC=0x870F003E=-2029060034=SQLO_QUE_BAD_HANDLE “Bad Queue Handle” DIA8555C An invalid message queue...

6

When Index Scans Attack!

We all know that table scans can be (but aren’t always) a negative thing. I have spent less time worrying about index scans, though. Index access = good, right? I thought I’d share a recent scenario where an index scan was very expensive. Maybe still better than a table scan, but with one index, I reduced the impact of a...

8

Scrambled Output from db2top

I don’t know about you, but I’m pretty addicted to db2top. I started using it way back when it was a download from Alphaworks. It is simply unparalleled for free real-time monitoring for DB2. No, it’s not full enough of a feature set to be your only monitoring tool, but I can barely troubleshoot a locking issue any more without...

2

Detailed Analysis of Individual Performance Metrics

Sometimes the things we studied in college are actually useful. As much as I hated my statistics professor, I still learned a lot that I frequently use. Maybe I don’t do many multiple regression problems these days, but I use standard deviation a lot. It is a concept that every DBA or really any IT professional who must analyze performance...

3

The Danger of FETCH FIRST ROW ONLY

There are a a vast array of things you can do in SQL. But just because you can doesn’t always mean that you should. I recently ran into an interesting situation with FETCH FIRST ROW ONLY. How the Problem Manifested The day after new code was deployed, a production database system that usually runs with 40% CPU utilization or less...