You can shoot yourself in the foot using DB2 if you are not careful. There are options that you can specify that may cause you to read data that is not really in the database. And, alternately, you can set things up so that you miss reading data that is actually in the database. How, you might be asking? Well, dirty reads will take care of the first one. Specifying ISOLATION(UR) implements read-through locks, which is sometimes referred to as a dirty read. It applies to read operations only. With this isolation level data may be read that never...
Monday, 23 November 2009
Tuesday, 17 November 2009
Replacing UNION with CASE
Posted on 12:58 by Unknown
When a UNION is required to put together data from multiple queries, you might be able to use a CASE statement instead. This is very useful, particularly when the data for each of the queries in the UNION come from the same table. The CASE statement can potentially enhance performance by minimizing the number of times the data is read.Let’s look at an example to clarify why: SELECT CREATOR, NAME, 'TABLE' FROM SYSIBM.SYSTABLES WHERE TYPE = 'T' UNION SELECT CREATOR, NAME, 'VIEW ' FROM SYSIBM.SYSTABLES WHERE TYPE =...
Tuesday, 3 November 2009
Deprecated Features Planned for DB2 X for z/OS
Posted on 09:15 by Unknown
Everyone is always interested in the latest and greatest features of their favorite DBMS, in this case DB2. But sometimes features get removed from the DBMS when a new version is released. According to the IBM teleconference on DB2 X for z/OS today, there are several features planned to be deprecated (i.e. removed). Let's briefly take a look at them.The first feature that will be removed is private protocol DRDA. This should come as no surprise to anybody since IBM has been indicating that private protocal distribution was on its way out for a...
Monday, 2 November 2009
New DB2 Twitter List
Posted on 07:51 by Unknown
Just a very quick post this morning to let all you DB2 Twitter folks out there know that I created a list of the DB2 tweeters I know about at http://twitter.com/craigmullins/db2-folks.If you are a DB2 professional and I left you off the list please leave a comment here or drop me an e-mail and I'll be happy to add y...
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