Date: Thu, 11 Mar 2021 09:57:12 -0500
From: Bruce Momjian <bruce@momjian.us>
To: Paul Smith <paul@pscs.co.uk>
Cc: pgsql-admin@lists.postgresql.org
Subject: Re: Using pg_upgrade to change from 32 to 64 bit.
Message-ID: <20210311145712.GE2469@momjian.us>
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On Thu, Mar 11, 2021 at 10:34:42AM +0000, Paul Smith wrote:
> Hi, we've been using 32 bit PostgreSQL 9.5 on Windows and are seeing how we
> could upgrade to v13 64 bit.
> 
> As far as I can see from the documentation and other discussion on the
> Internet, the only way to do this is to do a pg_dump and pg_restore, which
> could take a while with a large database.
> 
> Just "for kicks" I decided to try to use pg_upgrade to do it (on a test
> database).  The documentation seems to suggest that it won't work
> 
> "pg_upgrade does its best to make sure the old and new clusters are
> binary-compatible, e.g., by checking for compatible compile-time settings,
> *including 32/64-bit binaries*."
> 
> To my surprise, it seemed to work absolutely fine. I can start the new 64 bit
> cluster, and a quick check shows everything working OK.
> 
> Is this to be expected? Was it a fluke? I'd expect it to refuse to work rather
> than claim to work and give me a broken database.

Well, pg_upgrade checks all the pg_controldata fields that would affect
compatibility, so I guess it does work.  pg_upgrade only really cares
about the format of the database files, not the size of pointers used by
the binary.

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

  The usefulness of a cup is in its emptiness, Bruce Lee