Ben:
As I said in my previous post, you may get a lot of waits on this latch and
that is not necessarily something to be overly concerned about. However, you
can lower this number by increasing the PARALLEL_MAX_SERVERS parameter. This
is the maximum number of servers that are allowed to exist concurrently. Set
the value to:
(max # of concurrent PQO users) * (their max degree of parallelism) * 2
HTH!
--
Jon Walthour, OCDBA
Oracle DBA
Computer Horizons
Cincinnati, Ohio
> From: "Ben Jones" <[EMAIL PROTECTED]>
> Organization: Fat City Network Services, San Diego, California
> Reply-To: [EMAIL PROTECTED]
> Date: Fri, 15 Jun 2001 00:05:48 -0800
> To: Multiple recipients of list ORACLE-L <[EMAIL PROTECTED]>
> Subject: 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" <[EMAIL PROTECTED]>
>> Reply-To: [EMAIL PROTECTED]
>> To: Multiple recipients of list ORACLE-L <[EMAIL PROTECTED]>
>> 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" <[EMAIL PROTECTED]>
>>> To: Multiple recipients of list ORACLE-L <[EMAIL PROTECTED]>
>>> Date: 6/14/01 1:56:36 PM
>>>
>>
>>> Does anyone know what causes waits on this latch ?
>>>
>>> Thanks
>>> Ben
>>> _________________________________________________________________________
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>>> Author: Ben Jones
>>> INET: [EMAIL PROTECTED]
>>>
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>>
>> --
>> Please see the official ORACLE-L FAQ: http://www.orafaq.com
>> --
>> Author: Jon Walthour
>> INET: [EMAIL PROTECTED]
>>
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> _________________________________________________________________________
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>
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> Author: Ben Jones
> INET: [EMAIL PROTECTED]
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--
Author: Jon Walthour
INET: [EMAIL PROTECTED]
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