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From: Nathan Bossart <[email protected]>
To: Andres Freund <[email protected]>
Cc: Corey Huinker <[email protected]>
Cc: Jeff Davis <[email protected]>
Cc: Tom Lane <[email protected]>
Cc: Michael Paquier <[email protected]>
Cc: jian he <[email protected]>
Cc: Bruce Momjian <[email protected]>
Cc: Matthias van de Meent <[email protected]>
Cc: Magnus Hagander <[email protected]>
Cc: Stephen Frost <[email protected]>
Cc: Ashutosh Bapat <[email protected]>
Cc: Peter Smith <[email protected]>
Cc: PostgreSQL Hackers <[email protected]>
Cc: [email protected]
Subject: Re: Statistics Import and Export
Date: Wed, 5 Mar 2025 19:36:29 -0600
Message-ID: <Z8j8HXlIIGYPA9L8@nathan> (raw)
In-Reply-To: <rp6int5sqs5bn7g35brqz7w3t7il6tn2dgpm7tr3pev626wnc4@fi7a3enofhct>
References: <[email protected]>
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On Wed, Mar 05, 2025 at 08:17:53PM -0500, Andres Freund wrote:
> Right now --statistics more than doubles the number of queries that pg_dump
> issues. That's oviously noticeable locally, but it's going to be really
> noticeable when dumping across the network.
> 
> I think we need to do more to lessen the impact. Even leaving regression test
> performance aside, the time increase for the default pg_dump invocation will
> be painful for folks, particularly due to this being enabled by default.
> 
> One fairly easy win would be to stop issuing getAttributeStats() for
> non-expression indexes. In most cases that'll already drastically cut down on
> the extra queries.

Apologies if this has already been considered upthread, but would it be
possible to use one query to gather all the required information into a
sorted table?  At a glance, it looks to me like it might be feasible.  I
had a lot of luck with reducing the number per-object queries with that
approach recently (e.g., commit 2329cad).

-- 
nathan






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