Horton

Re: pg_resetwal is broken if run from v10 against older version of PG data directory

Michael Paquier <michael.paquier@gmail.com>

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From: Michael Paquier <michael.paquier@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Amit Kapila <amit.kapila16@gmail.com>, tushar <tushar.ahuja@enterprisedb.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2017-05-29T16:55:26Z
Lists: pgsql-hackers

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On Mon, May 29, 2017 at 9:00 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> So we need to prevent this, not try to make it work.  I don't think
> we can insist on a version match in pg_control, because part of the
> point of pg_resetxlog/pg_resetwal is to recover if pg_control is
> unreadable.  But I think we could look at PG_VERSION, which is only a
> text file.  In bad corruption scenarios, if that somehow got corrupted
> (which seems unlikely since it's never written to post-initdb),
> you could fill in the correct contents by hand and then
> pg_resetxlog/pg_resetwal would run.

Agreed. Shouldn't this be back-patched? PG_CONTROL_VERSION has not
been bumped between 9.4 and 9.5. Attached is a patch for HEAD.
-- 
Michael

Commits

  1. Prevent running pg_resetwal/pg_resetxlog against wrong-version data dirs.

  2. Rename "pg_xlog" directory to "pg_wal".