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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: Matthias van de Meent <boekewurm+postgres@gmail.com>, Robert Haas <robertmhaas@gmail.com>, Andres Freund <andres@anarazel.de>, PostgreSQL-development <pgsql-hackers@postgresql.org>, Noah Misch <noah@leadboat.com>
Date: 2021-04-07T15:52:17Z
Lists: pgsql-hackers 
On Wed, Apr 7, 2021 at 12:50 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:
> Thank you for updating the patches!
>
> I've done the final round of review:

All of the changes from your fixup patch are clear improvements, and
so I'll include them in the final commit. Thanks!

> For 0001 patch, we call PageTruncateLinePointerArray() only in the
> second pass over heap. I think we should note that the second pass is
> called only when we found/made LP_DEAD on the page. That is, if all
> dead tuples have been marked as LP_UNUSED by HOT pruning, the page
> would not be processed by the second pass, resulting in not removing
> LP_UNUSED at the end of line pointer array. So think we can call it in
> this case, i.g., when lpdead_items is 0 and tuples_deleted > 0 in
> lazy_scan_prune().

Maybe it would be beneficial to do that, but I haven't done it in the
version of the patch that I just pushed. We have run out of time to
consider calling PageTruncateLinePointerArray() in more places. I
think that the most important thing is that we have *some* protection
against line pointer bloat.

--
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).