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From: Laurenz Albe <[email protected]>
To: Greg Sabino Mullane <[email protected]>
To: Matthew Planchard <[email protected]>
Cc: [email protected]
Subject: Re: Dealing with SeqScans when Time-based Partitions Cut Over
Date: Fri, 19 Dec 2025 18:42:34 +0100
Message-ID: <[email protected]> (raw)
In-Reply-To: <CAKAnmmL3_WPtWRrCy1t3zJOcDConYA__so4FZj_Bzzza-inJjw@mail.gmail.com>
References: <[email protected]>
	<CAKAnmmL3_WPtWRrCy1t3zJOcDConYA__so4FZj_Bzzza-inJjw@mail.gmail.com>

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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