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help / color / mirror / Atom feedFrom: Bruce Momjian <[email protected]>
To: [email protected] <[email protected]>
Cc: Alexander Pyhalov <[email protected]>
Cc: PostgreSQL-development <[email protected]>
Cc: Andres Freund <[email protected]>
Cc: Tom Lane <[email protected]>
Cc: Tomas Vondra <[email protected]>
Cc: Julien Rouhaud <[email protected]>
Cc: Daniel Gustafsson <[email protected]>
Cc: Ilya Gladyshev <[email protected]>
Subject: Re: Partial aggregates pushdown
Date: Mon, 7 Aug 2023 14:30:54 -0400
Message-ID: <ZNE4XiLsV/[email protected]> (raw)
In-Reply-To: <OS3PR01MB6660DF84634EDAFC55D7B0009530A@OS3PR01MB6660.jpnprd01.prod.outlook.com>
References: <[email protected]>
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<[email protected]>
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<[email protected]>
<[email protected]>
<ZJMavbn5trJ/[email protected]>
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<[email protected]>
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On Mon, Jul 10, 2023 at 07:35:27AM +0000, [email protected] wrote:
> > > I will add a postgres_fdw option "check_partial_aggregate_support".
> > > This option is false, default.
> > > Only if this option is true, postgres_fdw connect to the remote server and get the version of the remote server.
> > > And if the version of the remote server is less than PG17, then partial aggregate push down to the remote server is
> > disable.
> >
> > Great!
> I have modified the program except for the point "if the version of the remote server is less than PG17".
> Instead, we have addressed the following.
> "If check_partial_aggregate_support is true and the remote server version is older than the local server
> version, postgres_fdw does not assume that the partial aggregate function is on the remote server unless
> the partial aggregate function and the aggregate function match."
> The reason for this is to maintain compatibility with any aggregate function that does not support partial
> aggregate in one version of V1 (V1 is PG17 or higher), even if the next version supports partial aggregate.
> For example, string_agg does not support partial aggregation in PG15, but it will support partial aggregation
> in PG16.
Just to clarify, I think you are saying:
If check_partial_aggregate_support is true and the remote server
version is older than the local server version, postgres_fdw
checks if the partial aggregate function exists on the remote
server during planning and only uses it if it does.
I tried to phrase it in a positive way, and mentioned the plan time
distinction. Also, I am sorry I was away for most of July and am just
getting to this.
--
Bruce Momjian <[email protected]> https://momjian.us
EDB https://enterprisedb.com
Only you can decide what is important to you.
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To: [email protected]
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Subject: Re: Partial aggregates pushdown
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