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Home -> Community -> Mailing Lists -> Oracle-L -> RE: Latch 'parallel query qref latch'
Jon,
Thanks for the email. My next question is fairly obvious...I'm getting a "lot" of waits on this latch (up to 5% of all waits) - how do I tune it ? (We've got a pretty typical environment here, a few big tables with parallel degree 4, on a 2 cpu box with 2G of RAM, and only a couple of end users doing big queries)...
Any guidelines (from anybody) would be much appreciated...
TIA
Ben
>From: "Jon Walthour" <jwalthour_at_mac.com>
>Reply-To: ORACLE-L_at_fatcity.com
>To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
>Subject: RE: Latch 'parallel query qref latch'
>Date: Thu, 14 Jun 2001 13:01:56 -0800
>
>
>
>Ben:
>
>The qref latch is obtained for each Parallel Query process. It
>is acquired before the queue buffers can be manipulated so that
>communication can take place between the various slave processes.
>The latch is acquired for putting messages into the buffer. You
>will generally see lots of misses for this latch since it is
>acquired with a nowait option.
>
>Jon Walthour, OCDBA
>Oracle DBA
>Computer Horizons
>Cincinnati, Ohio
>
> >--- Original Message ---
> >From: "Ben Jones" <benjonesz123_at_hotmail.com>
> >To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
> >Date: 6/14/01 1:56:36 PM
> >
>
> >Does anyone know what causes waits on this latch ?
> >
> >Thanks
> >Ben
> >_________________________________________________________________________
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> >--
> >Please see the official ORACLE-L FAQ: http://www.orafaq.com
> >--
> >Author: Ben Jones
> > INET: benjonesz123_at_hotmail.com
> >
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>--
>Please see the official ORACLE-L FAQ: http://www.orafaq.com
>--
>Author: Jon Walthour
> INET: jwalthour_at_mac.com
>
>Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
>San Diego, California -- Public Internet access / Mailing Lists
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-- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Ben Jones INET: benjonesz123_at_hotmail.com Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).Received on Fri Jun 15 2001 - 02:10:11 CDT
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