Re: Trouble with hashagg spill I/O pattern and costing

On Fri, Jun 05, 2020 at 06:51:34PM -0400, Alvaro Herrera wrote:
>On 2020-Jun-06, Tomas Vondra wrote:
>
>> On Fri, Jun 05, 2020 at 05:19:43PM -0400, Alvaro Herrera wrote:
>>
>> > Is this patch the only thing missing before this open item can be
>> > considered closed?
>>
>> I've already pushed this as 4cad2534da6d17067d98cf04be2dfc1bda8f2cd0,
>> sorry for not mentioning it in this thread explicitly.
>
>That's great to know, thanks. The other bit necessary to answer my
>question is whether do we need to do anything else in this area -- if
>no, then we can mark the open item as closed:
>https://wiki.postgresql.org/wiki/PostgreSQL_13_Open_Items#Open_Issues
>

Hmmm, good question.

There was some discussion about maybe tweaking the costing model to make
it a bit more pessimistic (assuming more random I/O or something like
that), but I'm not sure it's still needed. Increasing random_page_cost
for the temp tablespace did the trick for me.

So I'd say we can mark it as closed ...

regards

--
Tomas Vondra http://www.2ndQuadrant.com
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