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Re: 64-bit XIDs in deleted nbtree pages

Peter Geoghegan <pg@bowt.ie>

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From: Peter Geoghegan <pg@bowt.ie>
To: Masahiko Sawada <sawada.mshk@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Heikki Linnakangas <hlinnaka@iki.fi>
Date: 2021-02-19T06:12:01Z
Lists: pgsql-hackers

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On Thu, Feb 18, 2021 at 3:13 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:
> Agreed. Thanks for your explanation.

Attached is v5, which has some of the changes I talked about. Changes
from v4 include:

* Now only updates metapage during btvacuumcleanup() in the first
patch, which is enough to fix the existing
IndexVacuumInfo.num_heap_tuples issue.

* Restored _bt_getbuf() page-from-FSM XID check. Out of sheer paranoia.

* The second patch in the series now respects work_mem when sizing the
BTPendingRecycle array.

* New enhancement to the XID GlobalVisCheckRemovableFullXid() test
used in the second patch, to allow it to recycle even more pages.
(Still unsure of some of the details here.)

I would like to commit the first patch in a few days -- I refer to the
big patch that makes deleted page XIDs 64-bit/full. Can you take a
look at that one, Masahiko? That would be helpful. I can produce a bug
fix for the IndexVacuumInfo.num_heap_tuples issue fairly easily, but I
think that that should be written after the first patch is finalized
and committed.

The second patch (the new recycling optimization) will require more
work and testing.

Thanks!
-- 
Peter Geoghegan

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Recycle nbtree pages deleted during same VACUUM.

  2. VACUUM VERBOSE: Count "newly deleted" index pages.

  3. Use full 64-bit XIDs in deleted nbtree pages.

  4. Fix nbtree cleanup-only VACUUM stats inaccuracies.

  5. Fix undercounting in VACUUM VERBOSE output.

  6. Delete empty pages in each pass during GIST VACUUM.

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

  8. Allow VACUUM to be run with index cleanup disabled.

  9. Skip full index scan during cleanup of B-tree indexes when possible

  10. Do index FSM vacuuming sooner.

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

  12. Clean up API for ambulkdelete/amvacuumcleanup as per today's discussion.