| 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 |
| Message-ID: | 7bea462e-8c3e-0f8c-c7d5-f4daa12f3baf@postgrespro.ru |
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| Lists: | pgsql-hackers |
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
value.
--
regards,
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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