| From: | Konstantin Knizhnik <k(dot)knizhnik(at)postgrespro(dot)ru> |
|---|---|
| To: | PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Cc: | Yugo NAGATA <nagata(at)sraoss(dot)co(dot)jp> |
| Subject: | Improve join selectivity estimation using extended statistics |
| Date: | 2021-01-27 16:51:32 |
| Message-ID: | 71d67391-16a9-3e5e-b5e4-8f7fd32cc1b2@postgrespro.ru |
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| Lists: | pgsql-hackers |
Original thread is:
https://www.postgresql.org/message-id/flat/196f1e1a-5464-ed07-ab3c-0c9920564af7%40postgrespro.ru
Following Yugo's advice, I have splitted this patch into two:
1. Extending auto_explain extension to generate extended statistics in
case of bad selectivity estimation.
2. Taken in account extended statistics when computing join selectivity.
Now this thread will contain only patches for join selectivity estimation.
> However,
> IIUC, the clausesel patch uses only functional dependencies statistics for
> improving join, so my question was about possibility to consider MCV in the
> clausesel patch.
Sorry, do not have idea right now how to use MCV for better estimation
of join selectivity.
--
Konstantin Knizhnik
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company
| Attachment | Content-Type | Size |
|---|---|---|
| extended_statistic_join_selectivity-1.patch | text/x-patch | 7.9 KB |
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