Saturday, March 19, 2011

Tricky thing in EclipseLink/TopLink

Recently, I got problem when I used a DB adapter in SOA suite to insert a record into DB with a sequence. I always got the follow exception.
Exception Description: The sequence named [AVS_REQUEST_SEQ] is setup incorrectly. Its increment does not match its pre-allocation size.

Searched by google and found somebody wrote the follow.
Use 100 as a start value will resolve the problem: by default the start value is 1, when Eclipselink attempts to use the first allocated sequence value it's negative 1 - 100 + 1, that causes the exception.

The above setting solved the issue, but I got a sequence number is 52 instead of 1. I keep to search and found another answer.
You must change the DBAdapter properties in WebLogic deployments console, make the preallocationSize same as the one used for the sequence.
<config-property name="sequencePreallocationSize" value="1"/>

I checked my connection setting in DBAdapter, the value is really 50 and that is why I got a sequence from 52 (101-50+1).

The follow step is the way to change the preI've found it. It is in the dbAdapter connection pool's configuration of sequencePreallocationSize.

In the Weblogic's console:
1) Deployments->dbAdapter
2) Configuration's Tab
3) Click on
4) Click on your ConnectionPoolFactory
5) Properties' Tab
6) Change 'sequencePreallocationSize' property's value to 1. Press ENTER to actually change it.
7) Click Save button.
8) Go to Deployments
9) Check dbAdapter and click Update
10) Click Finish

This is really a tricky thing.