Date: Wed, 6 Sep 2023 21:00:15 -0400
From: Bruce Momjian <bruce@momjian.us>
To: David Rowley <dgrowleyml@gmail.com>
Cc: Git Queries <gitqueries0@gmail.com>, pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #18084: Count Mismatch Challenges During PostgreSQL Database
 Migration: Causes and Solutions
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On Thu, Sep  7, 2023 at 12:26:53PM +1200, David Rowley wrote:
> On Thu, 7 Sept 2023 at 11:17, Bruce Momjian <bruce@momjian.us> wrote:
> >
> > On Wed, Sep  6, 2023 at 11:11:05PM +0530, Git Queries wrote:
> > > Migration was performed using pg_dump.
> >
> > Uh, that is kind of a surprise since pg_dump/restore does a logical dump
> > --- none of the binary files are transfered, so it should always be
> > accurate.
> 
> I can't be certain, but I think the likely reason here is that the
> newly restored instance is fine and all indexes match the heap, but
> it's the source instance that has indexes with missing entries. Since
> the pg_dump queries are most likely to result in seqscans, then all
> rows will be returned and the new instance has no missing rows.

Yes, very good point.

-- 
  Bruce Momjian  <bruce@momjian.us>        https://momjian.us
  EDB                                      https://enterprisedb.com

  Only you can decide what is important to you.