From: | Tom Duffey <tduffey(at)trillitech(dot)com> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: Query memory usage |
Date: | 2010-05-16 00:08:40 |
Message-ID: | 802AEC6E-027E-4746-97B3-90C5FC4D33F9@trillitech.com |
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Lists: | pgsql-general |
On May 15, 2010, at 4:51 PM, Tom Lane wrote:
> Tom Duffey <tduffey(at)trillitech(dot)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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