Re: select count() out of memory - Mailing list pgsql-general

From tfinneid@student.matnat.uio.no
Subject Re: select count() out of memory
Date
Msg-id 43865.134.32.140.234.1193323338.squirrel@webmail.uio.no
Whole thread Raw
In response to Re: select count() out of memory  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: select count() out of memory  (Alvaro Herrera <alvherre@commandprompt.com>)
Re: select count() out of memory  ("Scott Marlowe" <scott.marlowe@gmail.com>)
List pgsql-general
> Alvaro Herrera <alvherre@commandprompt.com> writes:
>> tfinneid@student.matnat.uio.no wrote:
>>> I did a test previously, where I created 1 million partitions (without
>>> data) and I checked the limits of pg, so I think it should be ok.
>
>> Clearly it's not.
>
> You couldn't have tested it too much --- even planning a query over so
> many tables would take forever, and actually executing it would surely
> have run the system out of locktable space before it even started
> scanning.

And this is the testing, so you're right....

Its only the select on the root table that fails. Operations on a single
partitions is no problem.

> The partitioning facility is designed for partition counts in the tens,
> or maybe hundreds at the most.

Maybe, but it works even on 55000 partitions as long as the operations are
done against a partition and not the root table.


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