Horton

Re: pgsql: Avoid creation of the free space map for small heap relations, t

John Naylor <john.naylor@2ndquadrant.com>

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From: John Naylor <john.naylor@2ndquadrant.com>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Amit Kapila <akapila@postgresql.org>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2019-02-28T02:15:29Z
Lists: pgsql-hackers 
On Thu, Feb 28, 2019 at 7:24 AM Amit Kapila <amit.kapila16@gmail.com> wrote:
> > The flaw in my thinking was treating extension too similarly too
> > finding an existing block. With your patch clearing the local map in
> > the correct place, it seems the call at hio.c:682 is now superfluous?
>
> What if get some valid block from the first call to
> GetPageWithFreeSpace via local map which has required space?  I think
> in that case we will need the call at hio.c:682.  Am I missing
> something?

Are you referring to the call at line 393? Then the map will be
cleared on line 507 before we return that buffer.

-- 
John Naylor                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

Commits

  1. Clear the local map when not used.

  2. Remove unneeded argument from _bt_getstackbuf().

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