Re: Additional size of hash table is alway zero for hash aggregates - Mailing list pgsql-hackers

From Andres Freund
Subject Re: Additional size of hash table is alway zero for hash aggregates
Date
Msg-id 20200312191626.cd3i7iqawz4bcphm@alap3.anarazel.de
Whole thread Raw
In response to Additional size of hash table is alway zero for hash aggregates  (Pengzhou Tang <ptang@pivotal.io>)
Responses Re: Additional size of hash table is alway zero for hash aggregates  (Justin Pryzby <pryzby@telsasoft.com>)
Re: Additional size of hash table is alway zero for hash aggregates  (Pengzhou Tang <ptang@pivotal.io>)
Re: Additional size of hash table is alway zero for hash aggregates  (Pengzhou Tang <ptang@pivotal.io>)
List pgsql-hackers
Hi,


On 2020-03-12 16:35:15 +0800, Pengzhou Tang wrote:
> When reading the grouping sets codes, I find that the additional size of
> the hash table for hash aggregates is always zero, this seems to be
> incorrect to me, attached a patch to fix it, please help to check.

Indeed, that's incorrect. Causes the number of buckets for the hashtable
to be set higher - the size is just used for that.  I'm a bit wary of
changing this in the stable branches - could cause performance changes?

Greetings,

Andres Freund



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