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: 2018-11-20T12:48:19Z
Lists: pgsql-hackers 
On Tue, Nov 20, 2018 at 1:42 PM John Naylor <jcnaylor@gmail.com> wrote:
>
> I wrote:
>
> > On 11/19/18, Amit Kapila <amit.kapila16@gmail.com> wrote:
> > [ abortive states ]
> >> I think it might come from any other place between when you set it and
> >> before it got cleared (like any intermediate buffer and pin related
> >> API's).
> >
> > Okay, I will look into that.
>
> LockBuffer(), visibilitymap_pin(), and GetVisibilityMapPins() don't
> call errors at this level. I don't immediately see any additional good
> places from which to clear the local map.
>

LockBuffer()->LWLockAcquire() can error out.  Similarly,
ReadBuffer()->ReadBufferExtended() and calls below it can error ou.
To handle them, you need to add a call to clear local map in
Abortransaction code path.

-- 
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