[DB2-L] DB2 zOS - Baffled by an Update Lock - Got the answer

Walter Janißen

[DB2-L] DB2 zOS - Baffled by an Update Lock - Got the answer
Hi Adam

Great, that you finally found the answer.

I think, I have overlooked, that you said, access was using index only. That means, there couldn't be any other predicate, which made DB2 scanning through different pages.

Mit freundlichen Grüßen
Walter Janißen

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-----Ursprüngliche Nachricht-----
Von: IDUG DB2-L [mailto:[login to unmask email] Im Auftrag von Adam Baldwin
Gesendet: Donnerstag, 11. Februar 2010 15:25
An: [login to unmask email]
Betreff: Re: [DB2-L] DB2 zOS - Baffled by an Update Lock - Got the answer

Just in case any one is interested - I've spotted what's happening.

The row is variable length and the index only update causes the row length to increase. The updated row doesn't fit on the current page so DB2 goes page hunting with a U Lock.

So, an Index Only update can obtain U Locks.

Cheers, Adam

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_____________________________________________________________________

* IDUG North America * Tampa, Florida, * May 10-14 2010 * http://IDUG.ORG/NA *
* If you are going to attend only one conference this year, this is it! *
** The best DB2 technical sessions in the world
** NEW - IBM hands-on labs -> no additional charge
_____________________________________________________________________

If you need to change settings, http://www.idug.org/cgi-bin/wa?A0=DB2-L is the home of IDUG's DB2-L