从SQL Server 2000 OpenQuery到DB2 / AS400导致锁定

Question

Every morning we have a process that issues numerous queries (~10000) to DB2 on an AS400/iSeries/i6 (whatever IBM calls it nowadays), in the last 2 months, the operators have been complaining that our query locks a couple of files preventing them from completing their nightly processing. The queries are very simplisitic, eg

Select [FieldName] from OpenQuery('<LinkedServerName>', 'Select [FieldName] from [LibraryName].[FieldName] where [SomeField]=[SomeParameter]')

I am not an expert on the iSeries side of the house and was wondering if anyone had any insight on lock escalation from an AS400/Db2 perspective. The ID that is causing the lock has been confirmed to be the ID we registered our linked server as and we know its most likely us because the [Library] and [FileName] are consistent with the query we are issuing.

This has just started happening recently. Is it possible that our select statements which are causing the AS400 to escalate locks? The problem is they are not being released without manual intervention.

Answer 1

尝试在查询中添加“FOR READ ONLY”，然后在检索时不会锁定记录。

Answer 2

Writes to the files on the AS/400 side from an RPG/COBOL/JPL job program will cause a file lock (by default I think). The job will be unable to get this lock when you are reading. The solution we used was ... don't read the files when jobs are running. We created a big schedule sheet in excel and put all the sql servers' and as/400's jobs on it in times slots w/ color coding for importance and server. That way no conflicts or out of date extract files either.

Answer 3

You might have Commitment Control causing a lock for a Repeatable Read. Check the SQL Server ODBC connection associated with <linkedServerName> to change the commitment control.