On 11 October 2010 18:48, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Dean Rasheed <dean.a.rasheed@gmail.com> writes:
>> On 11 October 2010 18:37, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>>> Sure it would: an estimate of 30K would keep the planner from using
>>> hash aggregation.
>
>> Not if work_mem was 10MB.
>
> And? If the memory requirement actually fits, you're in good shape.
>
Yeah but the actual memory requirement, if it uses a hash aggregate,
is over 1GB, and could easily be much higher. It's also hard to kill,
because it eats up that memory so quickly.
Regards,
Dean
