| From: | Andrei Lepikhov <lepihov(at)gmail(dot)com> |
|---|---|
| To: | Attila Soki <atiware(at)gmx(dot)net>, Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at> |
| Cc: | pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: unstable query plan on pg 16,17,18 |
| Date: | 2026-02-27 15:35:31 |
| Message-ID: | 091eef0e-0271-47d1-aa47-439284e3f316@gmail.com |
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| Lists: | pgsql-performance |
On 27/2/26 16:00, Attila Soki wrote:
> On 27 Feb 2026, at 09:15, Andrei Lepikhov <lepihov(at)gmail(dot)com> wrote:
> I dont know the inner workings of analyze, is that normal that executing
> analyze on unchanged data can flip the plan? Does analyze select a
> random set of rows?
Yes, this is completely normal because ANALYZE works in a random way.
You can try using the Join-Order-Benchmark to see how running the
ANALYZE command can change the execution time of the same query,
sometimes by as much as ten times.
--
regards, Andrei Lepikhov,
pgEdge
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