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Re: New IndexAM API controlling index vacuum strategies

Masahiko Sawada <sawada.mshk@gmail.com>

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From: Masahiko Sawada <sawada.mshk@gmail.com>
To: Peter Geoghegan <pg@bowt.ie>
Cc: Robert Haas <robertmhaas@gmail.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>, Noah Misch <noah@leadboat.com>
Date: 2021-03-18T06:22:26Z
Lists: pgsql-hackers

Attachments

On Thu, Mar 18, 2021 at 12:23 PM Peter Geoghegan <pg@bowt.ie> wrote:
>
> On Wed, Mar 17, 2021 at 7:16 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:
> > Since I was thinking that always skipping index vacuuming on
> > anti-wraparound autovacuum is legitimate, skipping index vacuuming
> > only when we're really close to the point of going into read-only mode
> > seems a bit conservative, but maybe a good start. I've attached a PoC
> > patch to disable index vacuuming if the table's relfrozenxid is too
> > older than autovacuum_freeze_max_age (older than 1.5x of
> > autovacuum_freeze_max_age).
>
> Most anti-wraparound VACUUMs are really not emergencies, though. So
> treating them as special simply because they're anti-wraparound
> vacuums doesn't seem like the right thing to do. I think that we
> should dynamically decide to do this when (antiwraparound) VACUUM has
> already been running for some time. We need to delay the decision
> until it is almost certainly true that we really have an emergency.

That's a good idea to delay the decision until two_pass_strategy().

>
> Can you take what you have here, and make the decision dynamic? Delay
> it until we're done with the first heap scan? This will require
> rebasing on top of the patch I posted. And then adding a third patch,
> a little like the second patch -- but not too much like it.

Attached the updated patch that can be applied on top of your v3 patches.

Regards,

-- 
Masahiko Sawada
EDB:  https://www.enterprisedb.com/

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).