Re: Move pg_attribute.attcompression to earlier in struct for reduced size?

Tom Lane <tgl@sss.pgh.pa.us>

From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Michael Paquier <michael@paquier.xyz>, Andres Freund <andres@anarazel.de>, Dilip Kumar <dilipbalaut@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2021-05-27T13:34:08Z
Lists: pgsql-hackers
Robert Haas <robertmhaas@gmail.com> writes:
> On Thu, May 27, 2021 at 12:11 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> AFAIR, there are zero promises about how effective, or when effective,
>> changes in SET STORAGE will be.  And the number of complaints about
>> that has also been zero.  So I'm not sure why we need to do more for
>> SET COMPRESSION.  Especially since I'm unconvinced that recompressing
>> everything just to recompress everything would *ever* be worthwhile.

> I think it is good to have *some* way of ensuring that what you want
> the system to do, it is actually doing. If we have not a single
> operation in the system anywhere that can force recompression, someone
> who actually cares will be left with no option but a dump and reload.
> That is probably both a whole lot slower than something in the server
> itself and also a pretty silly thing to have to tell people to do.

[ shrug... ]  I think the history of the SET STORAGE option teaches us
that there is no such requirement, and you're inventing a scenario that
doesn't exist in the real world.

			regards, tom lane



Commits

  1. Remove forced toast recompression in VACUUM FULL/CLUSTER

  2. Rethink definition of pg_attribute.attcompression.

  3. Fix memory leak when de-toasting compressed values in VACUUM FULL/CLUSTER

  4. Re-order pg_attribute columns to eliminate some padding space.

  5. Add more TAP tests for pg_dump with attribute compression