Horton

Re: [HACKERS] Custom compression methods (mac+lz4.h)

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: Dilip Kumar <dilipbalaut@gmail.com>, Justin Pryzby <pryzby@telsasoft.com>, Andres Freund <andres@anarazel.de>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, David Steele <david@pgmasters.net>, Ildus Kurbangaliev <i.kurbangaliev@gmail.com>, Dmitry Dolgov <9erthalion6@gmail.com>, Andrey Borodin <x4mmm@yandex-team.ru>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2021-03-22T16:04:58Z
Lists: pgsql-hackers 
Robert Haas <robertmhaas@gmail.com> writes:
> On Mon, Mar 22, 2021 at 11:48 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> Possibly the former names should survive and the latter become
>> wrappers around them, not sure.  But we shouldn't be using the "4B"
>> terminology anyplace except this part of postgres.h.

> I would argue that it shouldn't be used any place at all, and that we
> ought to go the other direction and get rid of the existing macros -
> e.g. change #define VARATT_IS_1B_E to #define VARATT_IS_EXTERNAL
> instead of defining the latter as a no-value-added wrapper around the
> former. Maybe at one time somebody thought that the test for
> VARATT_IS_EXTERNAL might someday have more cases than just
> VARATT_IS_1B_E, but that's not looking like a good bet in 2021.

Maybe.  I think the original idea was exactly what the comment says,
to have a layer of macros that'd deal with endianness issues and no more.
That still seems like a reasonable plan to me, though perhaps it wasn't
executed very well.

			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.