Re: Dealing with SeqScans when Time-based Partitions Cut Over

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