Horton

Re: BUG: Postgres 14 + vacuum_defer_cleanup_age + FOR UPDATE + UPDATE

Thomas Munro <thomas.munro@gmail.com>

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From: Thomas Munro <thomas.munro@gmail.com>
To: Andres Freund <andres@anarazel.de>
Cc: Matthias van de Meent <boekewurm+postgres@gmail.com>, Michail Nikolaev <michail.nikolaev@gmail.com>, Peter Geoghegan <pg@bowt.ie>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>, Robert Haas <robertmhaas@gmail.com>, Mark Dilger <mark.dilger@enterprisedb.com>
Date: 2023-01-09T20:27:44Z
Lists: pgsql-hackers 
On Tue, Jan 10, 2023 at 8:34 AM Andres Freund <andres@anarazel.de> wrote:
> A different approach would be to represent fxids as *signed* 64bit
> integers. That'd of course loose more range, but could represent everything
> accurately, and would have a compatible on-disk representation on two's
> complement platforms (all our platforms). I think the only place that'd need
> special treatment is U64FromFullTransactionId() / its callers.  I think this
> might be the most robust approach.

It does sound like an interesting approach; it means you are free to
retreat arbitrarily without ever thinking about it, and by the
arguments given (LSN space required to consume fxids) it's still
'enough'.  Essentially all these bugs are places where the author
already believed it worked that way.

(Two's complement is required in the C23 draft.)

Commits

  1. Fix incorrect TAP test ordering

  2. pg_amcheck: Minor test speedups

  3. amcheck: Fix FullTransactionIdFromXidAndCtx() for xids before epoch 0

  4. amcheck: Fix ordering bug in update_cached_xid_range()

  5. Fix corruption due to vacuum_defer_cleanup_age underflowing 64bit xids

  6. Add hardening to catch invalid TIDs in indexes.

  7. Use full 64-bit XID for checking if a deleted GiST page is old enough.

  8. Avoid early reuse of btree pages, causing incorrect query results.