Re: Query memory usage - Mailing list pgsql-general

From Tom Duffey
Subject Re: Query memory usage
Date
Msg-id 802AEC6E-027E-4746-97B3-90C5FC4D33F9@trillitech.com
Whole thread Raw
In response to Re: Query memory usage  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: Query memory usage  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-general
On May 15, 2010, at 4:51 PM, Tom Lane wrote:

> Tom Duffey <tduffey@trillitech.com> writes:
>> I have a table with several hundred million rows of timestamped
>> values.  Using pg_dump we are able to dump the entire table to disk
>> no
>> problem.  However, I would like to retrieve a large subset of data
>> from this table using something like:
>
>> COPY (SELECT * FROM history WHERE timestamp > '2009-01-01') TO
>> STDOUT;
>
>> Executing this query causes our server to consume all available swap
>> and crash.
>
> What's being done on the client side with the data?  AFAIK that
> operation really shouldn't consume a lot of memory on the server side.
> It would help if you'd be more specific about which process is
> consuming
> swap space.

I am executing the query in psql at the command line and piping the
result to a file, e.g.,

psql < get_data.sql > data.sql

Tom

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