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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: 2021-03-18T06:41:33Z
Lists: pgsql-hackers 
On Wed, Mar 17, 2021 at 11:23 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:
> Attached the updated patch that can be applied on top of your v3 patches.

Some feedback on this:

* I think that we can afford to be very aggressive here, because we're
checking dynamically. And we're concerned about extremes only. So an
age of as high as 1 billion transactions seems like a better approach.
What do you think?

* I think that you need to remember that we have decided not to do any
more index vacuuming, rather than calling
check_index_cleanup_xid_limit() each time -- maybe store that
information in a state variable.

This seems like a good idea because we should try to avoid changing
back to index vacuuming having decided to skip it once. Also, we need
to refer to this in lazy_scan_heap(), so that we avoid index cleanup
having also avoided index vacuuming. This is like the INDEX_CLEANUP =
off case, which is also only for emergencies. It is not like the
SKIP_VACUUM_PAGES_RATIO case, which is just an optimization.

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. 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).