Horton

Re: [HACKERS] Custom compression methods

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

View thread View on postgr.es
From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Dilip Kumar <dilipbalaut@gmail.com>, 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 Developers <pgsql-hackers@lists.postgresql.org>
Date: 2020-11-24T18:21:38Z
Lists: pgsql-hackers 
Robert Haas <robertmhaas@gmail.com> writes:
> On Tue, Nov 24, 2020 at 10:47 AM Dilip Kumar <dilipbalaut@gmail.com> wrote:
>> For the compression routine name, I did not include "Am" because
>> currently, we are storing the compression method in the new catalog
>> "pg_compression" not in the pg_am.   So are you suggesting that we
>> should store the compression methods also in the pg_am instead of
>> creating a new catalog?  IMHO, storing the compression methods in a
>> new catalog is a better option instead of storing them in pg_am
>> because actually, the compression methods are not the same as heap or
>> index AMs, I mean they are actually not the access methods.  Am I
>> missing something?

> Oh, I thought it had been suggested in previous discussions that these
> should be treated as access methods rather than inventing a whole new
> concept just for this, and it seemed like a good idea to me. I guess I
> missed the fact that the patch wasn't doing it that way. Hmm.

FWIW, I kind of agree with Robert's take on this.  Heap and index AMs
are pretty fundamentally different animals, yet we don't have a problem
sticking them in the same catalog.  I think anything that is related to
storage access could reasonably go into that catalog, rather than
inventing a new one.

			regards, tom lane

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.