Re: Add semi-join pushdown to postgres_fdw

From: Alexander Pyhalov <a(dot)pyhalov(at)postgrespro(dot)ru>
To: Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com>
Cc: "Fujii(dot)Yuki(at)df(dot)MitsubishiElectric(dot)co(dot)jp" <Fujii(dot)Yuki(at)df(dot)mitsubishielectric(dot)co(dot)jp>, Ashutosh Bapat <ashutosh(dot)bapat(dot)oss(at)gmail(dot)com>, Pgsql Hackers <pgsql-hackers(at)postgresql(dot)org>, Ian Lawrence Barwick <barwick(at)gmail(dot)com>
Subject: Re: Add semi-join pushdown to postgres_fdw
Date: 2023-01-20 09:00:04
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Tomas Vondra писал 2023-01-19 20:49:
> I took a quick look at the patch. It needs a rebase, although it
> applies
> fine using patch.
> A couple minor comments:
> 1) addl_conds seems a bit hard to understand, I'd use either the full
> wording (additional_conds) or maybe extra_conds

Renamed to additional_conds.

> 2) some of the lines got quite long, and need a wrap
Splitted some of them. Not sure if it's enough.

> 3) unknown_subquery_rels name is a bit misleading - AFAIK it's the rels
> that can't be referenced from upper rels (per what the .h says). So
> they
> are known, but hidden. Is there a better name?

Renamed to hidden_subquery_rels. These are rels, which can't be referred
to from upper join levels.

> 4) joinrel_target_ok() needs a better comment, explaining *when* the
> reltarget is safe for pushdown. The conditions are on the same row, but
> the project style is to break after '&&'.

Added comment. It seems to be a rephrasing of lower comment in

Best regards,
Alexander Pyhalov,
Postgres Professional

Attachment Content-Type Size
v4-0001-postgres_fdw-add-support-for-deparsing-semi-joins.patch text/x-diff 49.7 KB

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