| From: | Bruce Momjian <bruce(at)momjian(dot)us> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Stephen Frost <sfrost(at)snowman(dot)net>, Shruthi Gowda <gowdashru(at)gmail(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>, Tom Kincaid <tomjohnkincaid(at)gmail(dot)com>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Thomas Munro <thomas(dot)munro(at)gmail(dot)com>, PostgreSQL Development <pgsql-hackers(at)postgresql(dot)org>, Masahiko Sawada <masahiko(dot)sawada(at)2ndquadrant(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Subject: | Re: preserving db/ts/relfilenode OIDs across pg_upgrade (was Re: storing an explicit nonce) |
| Date: | 2021-08-24 18:49:00 |
| Message-ID: | 20210824184900.GD21369@momjian.us |
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| Lists: | pgsql-hackers |
On Tue, Aug 24, 2021 at 02:34:26PM -0400, Robert Haas wrote:
> On Tue, Aug 24, 2021 at 2:16 PM Bruce Momjian <bruce(at)momjian(dot)us> wrote:
> > One other issue --- the more that pg_upgrade preserves, the more likely
> > pg_upgrade will break when some internal changes happen in Postgres.
> > Therefore, if you want pg_upgrade to preserve something, you have to
> > have a good reason --- even code simplicity might not be a sufficient
> > reason.
>
> While I accept that as a general principle, I don't think it's really
> applicable in this case. pg_upgrade already knows all about
> relfilenodes; it has a source file called relfilenode.c. I don't see
> that a pg_upgrade that preserves relfilenodes is any more or less
> likely to break in the future than a pg_upgrade that renumbers all the
> files so that the relation OID and the relfilenode are equal. You've
> got about the same amount of reliance on the on-disk layout either
> way.
I was making more of a general statement that preservation can be
problematic and its impact must be researched.
--
Bruce Momjian <bruce(at)momjian(dot)us> https://momjian.us
EDB https://enterprisedb.com
If only the physical world exists, free will is an illusion.
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