Horton

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

Mark Dilger <mark.dilger@enterprisedb.com>

View thread View on postgr.es
From: Mark Dilger <mark.dilger@enterprisedb.com>
To: Andres Freund <andres@anarazel.de>
Cc: Matthias van de Meent <boekewurm+postgres@gmail.com>, Michail Nikolaev <michail.nikolaev@gmail.com>, Thomas Munro <thomas.munro@gmail.com>, Peter Geoghegan <pg@bowt.ie>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>, Robert Haas <robertmhaas@gmail.com>
Date: 2023-01-09T21:55:02Z
Lists: pgsql-hackers 

> On Jan 9, 2023, at 11:34 AM, Andres Freund <andres@anarazel.de> wrote:
> 
> 1) Because ctx->next_xid is set after the XidFromFullTransactionId() call in
> update_cached_xid_range(), we end up using the xid 0 (or an outdated value in
> subsequent calls) to determine whether epoch needs to be reduced.

Can you say a bit more about your analysis here, preferably with pointers to the lines of code you are analyzing?  Does the problem exist in amcheck as currently committed, or are you thinking about a problem that arises only after applying your patch?  I'm a bit fuzzy on where xid 0 gets used.

Thanks

—
Mark Dilger
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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.