Re: POC: GROUP BY optimization

From: "Andrey V(dot) Lepikhov" <a(dot)lepikhov(at)postgrespro(dot)ru>
To: Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com>, Teodor Sigaev <teodor(at)sigaev(dot)ru>
Cc: Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, PostgreSQL Developers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: POC: GROUP BY optimization
Date: 2022-02-10 09:00:37
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On 1/22/22 01:34, Tomas Vondra wrote:

I rebased (with minor fixes) this patch onto current master.

Also, second patch dedicated to a problem of "varno 0" (fake_var).
I think, this case should make the same estimations as in the case of
varno != 0, but no any stats found. So I suppose to restrict number of
groups with min of a number of incoming tuples and DEFAULT_NUM_DISTINCT

Andrey Lepikhov
Postgres Professional

Attachment Content-Type Size
0002-Use-default-restriction-for-number-of-groups.txt text/plain 2.1 KB
v20220210-0001-GROUP-BY-reordering.patch text/x-patch 100.0 KB

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