Message-ID: <a443f2322c61ab38d6b3ac3915fe0afaf0235b93.camel@j-davis.com>
Subject: Re: Statistics import and export: difference in statistics of
 materialized view dumped
From: Jeff Davis <pgsql@j-davis.com>
To: Tom Lane <tgl@sss.pgh.pa.us>, Ashutosh Bapat
 <ashutosh.bapat.oss@gmail.com>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>, Corey Huinker
	 <corey.huinker@gmail.com>
Date: Tue, 11 Mar 2025 08:21:43 -0700
In-Reply-To: <1427602.1741702648@sss.pgh.pa.us>
References: 
	<CAExHW5s47kmubpbbRJzSM-Zfe0Tj2O3GBagB7YAyE8rQ-V24Uw@mail.gmail.com>
	 <1427602.1741702648@sss.pgh.pa.us>
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On Tue, 2025-03-11 at 10:17 -0400, Tom Lane wrote:
> Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> writes:
> > After fixing the statistics difference in dumps of tables with
> > indexes, I now see difference in statistics of materialized view
> > dump
> > in the test I am developing at [1] (see the latest patches there).
>=20
> Are you doing the restore in parallel by any chance?=C2=A0 I had a todo
> item to revisit the dependencies that pg_dump is creating for stats
> items, because they looked wrong to me, ie inadequate to guarantee
> correct restore order.

It's creating a dependency on the relation and a boundary dependency on
the postDataBound (unless it's an index, or an MV that got pushed to
SECTION_POST_DATA).

I suspect what we need here is a dependency on the MV *data*, because
that's doing a heap swap, which resets the stats. Looking into it.

Regards,
	Jeff Davis