Horton

Re: WIP: Avoid creation of the free space map for small tables

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: jcnaylor@gmail.com
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2018-11-29T12:47:56Z
Lists: pgsql-hackers 
On Thu, Nov 29, 2018 at 3:07 PM John Naylor <jcnaylor@gmail.com> wrote:
> > Few more comments:
> > -------------------------------
> > 1. I think we can add some test(s) to test the new functionality, may
> > be something on the lines of what Robert has originally provided as an
> > example of this behavior [1].
>
> Done. I tried adding it to several schedules, but for some reason
> vacuuming an empty table failed to truncate the heap to 0 blocks.
> Putting the test in its own group fixed the problem, but that doesn't
> seem ideal.
>

It might be because it fails the should_attempt_truncation() check.
See below code:

if (should_attempt_truncation(vacrelstats))
lazy_truncate_heap(onerel, vacrelstats, vac_strategy);


-- 
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com

Commits

  1. Improve code comments in b0eaa4c51b.

  2. During pg_upgrade, conditionally skip transfer of FSMs.

  3. Add more tests for FSM.

  4. Doc: Update the documentation for FSM behavior for small tables.

  5. Make FSM test portable.

  6. Avoid creation of the free space map for small heap relations, take 2.

  7. Move page initialization from RelationAddExtraBlocks() to use, take 2.

  8. Avoid creation of the free space map for small heap relations.

  9. In bootstrap mode, don't allow the creation of files if they don't already