Horton

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

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

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Michael Paquier <michael@paquier.xyz>, Justin Pryzby <pryzby@telsasoft.com>, Andres Freund <andres@anarazel.de>, pgsql-hackers@postgresql.org, Dilip Kumar <dilipbalaut@gmail.com>
Date: 2021-05-26T19:31:28Z
Lists: pgsql-hackers

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Robert Haas <robertmhaas@gmail.com> writes:
> On Wed, May 26, 2021 at 11:13 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> * As things stand here, once you've applied ALTER ... SET COMPRESSION
>> to select a specific method, there is no way to undo that and go
>> back to the use-the-default setting.  All you can do is change to
>> explicitly select the other method.  Should we invent "ALTER ...
>> SET COMPRESSION default" or the like to cover that?

> Yes. Irreversible catalog changes are bad.

Here's an add-on 0004 that does that, and takes care of assorted
silliness in the grammar and docs --- did you know that this patch
caused
	alter table foo alter column bar set ;
to be allowed?

I think this is about ready to commit now (though I didn't yet nuke
GetDefaultToastCompression).

			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