Re: Dealing with SeqScans when Time-based Partitions Cut Over - Mailing list pgsql-general

From Laurenz Albe
Subject Re: Dealing with SeqScans when Time-based Partitions Cut Over
Date
Msg-id 64ccdcb7b15a17cbf610854e51cd8235c246cca8.camel@cybertec.at
Whole thread Raw
In response to Re: Dealing with SeqScans when Time-based Partitions Cut Over  (Greg Sabino Mullane <htamfids@gmail.com>)
Responses Re: Dealing with SeqScans when Time-based Partitions Cut Over
List pgsql-general
On Fri, 2025-12-19 at 09:49 -0500, Greg Sabino Mullane wrote:
> If this is still an issue after you check David's theory about premature analyzing,
> another approach is to pre-populate and pre-analyze future tables. Something like this:
>
> * disable autovac on the future table
> * detach the table from the main partition
> * insert a few hundred thousand rows into it, then run analyze on it
> * can pull rows from a current table, or just use random data on a key column- whatever is enough to generate "good"
stats
> * delete the rows - the stats will remain
> * reattach the table
> * enable autovac if you like; I would not

I doubt that that is good advice.  For one, wrong statistics are not necessarily
better than no statistics.  Disabling autovacuum is dangerous - and re-enabling
it would trigger another autovacuum, which would undo your efforts.
*Not* re-enabling autovacuum is not an option, unless you schedule explicit
VACUUM runs on the partition.

Yours,
Laurenz Albe



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