From: | Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at> |
---|---|
To: | David Rowley <dgrowleyml(at)gmail(dot)com>, Pól Ua Laoínecháin <linehanp(at)tcd(dot)ie> |
Cc: | PostgreSQL General <pgsql-general(at)lists(dot)postgresql(dot)org> |
Subject: | Re: EXPLAIN (ANALYZE, BUFFERS) - puzzling numbers for a simple query. |
Date: | 2021-06-04 12:55:14 |
Message-ID: | fd14173d698cf45d5784c459f63a982aa800b9e6.camel@cybertec.at |
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Lists: | pgsql-general |
On Sat, 2021-06-05 at 00:12 +1200, David Rowley wrote:
> As for the call to generate_series, you're not likely to ever get any
> great estimation from that. The number of rows returned by a call to
> that particular function are just whatever is set in pg_proc.prorows,
> in this case, 1000. The other generate_series functions which take
> INT and BIGINT inputs do have a prosupport function.
"generate_series" has a support function from v12 on:
EXPLAIN SELECT * FROM generate_series(1, 25);
QUERY PLAN
═════════════════════════════════════════════════════════════════════
Function Scan on generate_series (cost=0.00..0.25 rows=25 width=4)
(1 row)
Yours,
Laurenz Albe
--
Cybertec | https://www.cybertec-postgresql.com
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