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: John Naylor <john.naylor@2ndquadrant.com>
Cc: Mithun Cy <mithun.cy@enterprisedb.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2019-03-08T11:45:31Z
Lists: pgsql-hackers 
On Wed, Mar 6, 2019 at 5:19 PM John Naylor <john.naylor@2ndquadrant.com> wrote:
>
> On Fri, Jan 25, 2019 at 9:50 AM Amit Kapila <amit.kapila16@gmail.com> wrote:
> > Once we agree on the code, we need to test below scenarios:
> > (a) upgrade from all supported versions to the latest version
> > (b) upgrade standby with and without using rsync.
>
> Although the code hasn't been reviewed yet, I went ahead and tested
> (a) on v21 of the pg_upgrade patch [1]. To do this I dumped out a 9.4
> instance with the regression database and restored it to all supported
> versions. To make it work with pg_upgrade, I first had to drop tables
> with oids, drop functions referring to C libraries, and drop the
> later-removed '=>' operator. Then I pg_upgrade'd in copy mode from all
> versions to HEAD with the patch applied. pg_upgrade worked without
> error, and the following query returned 0 bytes on all the new
> clusters:
>
> select sum(pg_relation_size(oid, 'fsm')) as total_fsm_size
> from pg_class where relkind in ('r', 't')
> and pg_relation_size(oid, 'main') <= 4 * 8192;
>
> The complementary query (> 4 * 8192) returned the same number of bytes
> as in the original 9.4 instance.
>

Thanks, the tests done by you are quite useful.  I have given a few
comments as a response to your previous email.

-- 
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