Re: out of memory for query result - Mailing list pgsql-general

From Larry Rosenman
Subject Re: out of memory for query result
Date
Msg-id F6616E0E81AC0841B1F9DD252F7C4B55041A59@ausmaildd.aus.pervasive.com
Whole thread Raw
In response to out of memory for query result  (Francisco Reyes <lists@stringsutils.com>)
List pgsql-general
Sven Willenberger wrote:

> OK, that I do see; I guess I never noticed it on the other (i386)
> machine as the memory never exceeded the max amount allowed by the
> tunables. That raises a question though:
>
> Using identical data and identical queries, why would the amd64 system
> using postgresql 8.1.3 be using some 2/3s more memory to store the
> query results before output than the i386 system using postgresql
> 8.0.4?
>
> amd64 system:
>   PID USERNAME  THR PRI NICE   SIZE    RES STATE  C   TIME   WCPU CMD
>  8193 svenw       1   5    0  1516M  1475M ttyin  1   0:15  0.00% psql
>
> i386 system:
>   PID USERNAME  THR PRI NICE   SIZE    RES STATE  C   TIME   WCPU CMD
> 61263 svenw       1   5    0   972M   956M ttyin  2   0:27  0.00% psql
>
> These are the final stages after the file has flushed (this was run on
> the prior month's data which had fewer results). This would either
> point to an issue with a) amd64 memory allocation or b) palloc
> interacting with 64bit memory or c) some other change.

My suspicion is that it has to do with pointers being 8 bytes vs 4 bytes
in amd64.


--
Larry Rosenman
Database Support Engineer

PERVASIVE SOFTWARE. INC.
12365B RIATA TRACE PKWY
3015
AUSTIN TX  78727-6531

Tel: 512.231.6173
Fax: 512.231.6597
Email: Larry.Rosenman@pervasive.com
Web: www.pervasive.com

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