From: | Richard Guo <guofenglinux(at)gmail(dot)com> |
---|---|
To: | jian he <jian(dot)universality(at)gmail(dot)com> |
Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, Tender Wang <tndrwang(at)gmail(dot)com>, Paul George <p(dot)a(dot)george19(at)gmail(dot)com>, Andy Fan <zhihuifan1213(at)163(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, pgsql-hackers(at)lists(dot)postgresql(dot)org |
Subject: | Re: Eager aggregation, take 3 |
Date: | 2024-10-29 07:51:37 |
Message-ID: | CAMbWs4892MV=hE2rBYchtjQtZ-kCzriuyupj=h-eX30ic_1nDQ@mail.gmail.com |
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On Fri, Oct 18, 2024 at 12:44 PM jian he <jian(dot)universality(at)gmail(dot)com> wrote:
> 1. root->parse->resultRelation > 0
> just be 100% sure we are only dealing with SELECT, or we can add
> Assert at the end of setup_eager_aggregation.
Can GROUP BY clauses be used in INSERT/UPDATE/DELETE/MERGE statements?
If not, I think there is no need to check 'resultRelation > 0', as
setup_eager_aggregation already checks for GROUP BY clauses.
> 2. join type is FULL JOIN, (i am not sure about other Semijoins and
> anti-semijoins types).
The presence of a FULL JOIN does not preclude the use of eager
aggregation. We still can push a partial aggregation down to a level
that is above the FULL JOIN.
> 3. root->parse->windowClause != NIL
Why does the presence of windowClause prevent the use of eager
aggregation?
> lack doc entry in doc/src/sgml/config.sgml
> we can put after varlistentry enable_bitmapscan
> we can at least mention that
> enable_eager_aggregate, The default value is <literal>off</literal>.
Yeah, that's what I need to do.
Thanks
Richard
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