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Re: New IndexAM API controlling index vacuum strategies

Peter Geoghegan <pg@bowt.ie>

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From: Peter Geoghegan <pg@bowt.ie>
To: Masahiko Sawada <sawada.mshk@gmail.com>
Cc: Robert Haas <robertmhaas@gmail.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>, Noah Misch <noah@leadboat.com>
Date: 2021-03-23T03:33:55Z
Lists: pgsql-hackers 
On Mon, Mar 22, 2021 at 8:28 PM Peter Geoghegan <pg@bowt.ie> wrote:
> You seem to be concerned about a similar contradiction. In fact it's
> *very* similar contradiction, because this new GUC is naturally a
> "sibling GUC" of both vacuum_freeze_table_age and
> autovacuum_vacuum_max_age (the "units" are the same, though the
> behavior that each GUC triggers is different -- but
> vacuum_freeze_table_age and autovacuum_vacuum_max_age are both already
> *similar and different* in the same way). So perhaps the solution
> should be similar -- silently interpret the setting of the new GUC to
> resolve the contradiction.

More concretely, maybe the new GUC is forced to be 1.05 of
vacuum_freeze_table_age. Of course that scheme is a bit arbitrary --
but so is the existing 0.95 scheme.

There may be some value in picking a scheme that "advertises" that all
three GUCs are symmetrical, or at least related -- all three divide up
the table's XID space.

-- 
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. Don't truncate heap when VACUUM's failsafe is in effect.

  2. Teach VACUUM to bypass unnecessary index vacuuming.

  3. Add wraparound failsafe to VACUUM.

  4. Truncate line pointer array during VACUUM.

  5. Remove tupgone special case from vacuumlazy.c.

  6. Refactor lazy_scan_heap() loop.

  7. Propagate parallel VACUUM's buffer access strategy.

  8. Simplify state managed by VACUUM.

  9. Notice that heap page has dead items during VACUUM.

  10. Adjust lazy_scan_heap() accounting comments.

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

  12. Fix some problems with VACUUM (INDEX_CLEANUP FALSE).