Re: out of memory during query execution

From: DANTE ALEXANDRA <ALEXANDRA(dot)DANTE(at)BULL(dot)NET>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Kevin Murphy <murphy(at)genome(dot)chop(dot)edu>, Chris Browne <cbbrowne(at)acm(dot)org>, pgsql-general(at)postgresql(dot)org
Subject: Re: out of memory during query execution
Date: 2005-12-21 09:41:56
Message-ID: 43A92364.8090204@BULL.NET
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Hello,

Just to give you explanation, I will try to explain you why I have set
the "work_mem" to 64MB.

I noticed that some of the queries have finished with an "out of memory"
because the file system on which temporary files were created was to
small. Consequently, I have increase the size of this file system and I
have set work_mem to 64MB. The query still continued to swap into
temporary files but did not finish with an "out of memory".

The next steps for me will be to :
- decrease the work_mem
- try to build PostGreSQL with 32 bits and the option "-bmaxdata:0x40000000"
- try to build PostGreSQL with 64 bits.

I will give you the results as soon as possible.

Thank you for your help.
Regards,
Alexandra DANTE

Tom Lane a écrit :

>Kevin Murphy <murphy(at)genome(dot)chop(dot)edu> writes:
>
>
>>I'm certainly not an AIX expert, but I remember my 32-bit AIX programs
>>being limited to 256MB of heap by default.
>>
>>
>
>Hmm ... if that's the case then it'd probably explain the problem.
>Alexandra had work_mem set to 64MB, so the two hashes and sort would
>think they could use 3/4ths of the available heap; given that there
>are other needs and our management of memory-use limitations is fairly
>sloppy, that could easily translate into running out.
>
>So the answer is either to increase the available heap or reduce
>work_mem to a smaller fraction of it.
>
> regards, tom lane
>
>
>

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