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From: David Rowley <dgrowleyml@gmail.com>
Date: Wed, 2 Apr 2025 10:06:59 +1300
Message-ID: <CAApHDvpT0Y1BfYgeWz+PkKaLBEff1izYOAjNSibhBTNFEdqLtg@mail.gmail.com>
Subject: Re: Add estimated hit ratio to Memoize in EXPLAIN to explain cost adjustment
To: Ilia Evdokimov <ilya.evdokimov@tantorlabs.com>
Cc: Robert Haas <robertmhaas@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>, 
	Lukas Fittl <lukas@fittl.com>, Daniel Gustafsson <daniel@yesql.se>, 
	PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, 
	Nikolay Samokhvalov <samokhvalov@gmail.com>, Andrei Lepikhov <lepihov@gmail.com>
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On Tue, 1 Apr 2025 at 20:52, Ilia Evdokimov
<ilya.evdokimov@tantorlabs.com> wrote:
> With the feature freeze coming up soon, I=E2=80=99d like to ask: do we pl=
an to
> include this patch in v18?

I don't think there's a clear enough consensus yet on what EXPLAIN
should display. We'd need that beforehand. There are now less than 7
days to get that, so it might be unrealistic.

I tried to move things along to address Tom's concern about not
wanting to show this in EXPLAIN's standard output. I suggested in [1]
that we could use EXPLAIN ANALYZE, but nobody commented on that.
EXPLAIN ANALYZE is much more verbose than EXPLAIN already, and if we
put these in EXPLAIN ANALYZE then the viewer can more easily compare
planned vs actual. I had mentioned that Hash Join does something like
this for buckets.

David

[1] https://postgr.es/m/CAApHDvqPkWmz1Lq23c9CD+mAW=3DhgPrD289tC30f3H1f6Ng59=
+g@mail.gmail.com