Horton

Re: [HACKERS] Custom compression methods

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Justin Pryzby <pryzby@telsasoft.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Andrew Dunstan <andrew@dunslane.net>, Dilip Kumar <dilipbalaut@gmail.com>, Alvaro Herrera <alvherre@alvh.no-ip.org>, Andres Freund <andres@anarazel.de>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, Alexander Korotkov <a.korotkov@postgrespro.ru>, David Steele <david@pgmasters.net>, Ildus Kurbangaliev <i.kurbangaliev@gmail.com>, Dmitry Dolgov <9erthalion6@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2021-03-24T17:30:26Z
Lists: pgsql-hackers 
On Wed, Mar 24, 2021 at 1:24 PM Justin Pryzby <pryzby@telsasoft.com> wrote:
> I think it's not specific to pg_upgrade, but any pg_dump |pg_restore.
>
> The analogy with tablespaces is restoring from a cluster where the tablespace
> is named "vast" to one where it's named "huge".  I do this by running
> PGOPTIONS=-cdefault_tablespace=huge pg_restore --no-tablespaces
>
> So I thinks as long as --no-toast-compression does the corresponding thing, the
> "restore with alternate compression" case is handled fine.

I think you might be missing the point. If you're using pg_dump and
pg_restore, you can pass --no-toast-compression if you want. But if
you're using pg_upgrade, and it's internally calling pg_dump
--binary-upgrade, then you don't have control over what options get
passed. So --no-toast-compression is just fine for people who are
dumping and restoring, but it's no help at all if you want to switch
TOAST compression methods while doing a pg_upgrade. However, what does
help with that is sticking with what Tom committed before rather than
changing to what he's proposing now.

If you like his current proposal, that's fine with me, as long as
we're on the same page about what happens if we adopt it.

-- 
Robert Haas
EDB: http://www.enterprisedb.com

Commits

  1. docs: Update TOAST storage docs for configurable compression.

  2. Further tweaking of pg_dump's handling of default_toast_compression.

  3. Fix interaction of TOAST compression with expression indexes.

  4. Tidy up more loose ends related to configurable TOAST compression.

  5. Short-circuit slice requests that are for more than the object's size.

  6. Mostly-cosmetic adjustments of TOAST-related macros.

  7. Remove useless configure probe for <lz4/lz4.h>.

  8. Error on invalid TOAST compression in CREATE or ALTER TABLE.

  9. docs: Fix omissions related to configurable TOAST compression.

  10. More code cleanup for configurable TOAST compression.

  11. Bring configure support for LZ4 up to snuff.

  12. Make compression.sql regression test independent of default.

  13. Use valid compression method in brin_form_tuple

  14. Fix up pg_dump's handling of per-attribute compression options.

  15. Allow configurable LZ4 TOAST compression.

  16. Fix inconsistencies in the code

  17. Mostly-cosmetic improvements in memory chunk header alignment coding.

  18. Allow numeric to use a more compact, 2-byte header in many cases.