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

On Fri, Jan 25, 2019 at 9:50 AM Amit Kapila <amit(dot)kapila16(at)gmail(dot)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.

To make it easy to find, the latest regression test patch, which is
intended to be independent of block-size, was in [2].

[1] https://www.postgresql.org/message-id/CACPNZCu4cOdm3uGnNEGXivy7Gz8UWyQjynDpdkPGabQ18_zK6g%40mail.gmail.com

[2] https://www.postgresql.org/message-id/CACPNZCsWa%3Ddd0K%2BFiODwM%3DLEsepAHVJCoSx2Avew%3DxBEX3Ywjw%40mail.gmail.com

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