Horton

Re: [HACKERS] Custom compression methods

Justin Pryzby <pryzby@telsasoft.com>

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From: Justin Pryzby <pryzby@telsasoft.com>
To: Andres Freund <andres@anarazel.de>
Cc: Robert Haas <robertmhaas@gmail.com>, 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>, pgsql-hackers@lists.postgresql.org
Date: 2021-03-18T01:45:02Z
Lists: pgsql-hackers 
On Wed, Mar 17, 2021 at 02:50:34PM -0700, Andres Freund wrote:
> On 2021-03-17 16:01:58 -0400, Robert Haas wrote:
> > > - why is HIDE_TOAST_COMPRESSION useful? Doesn't quite seem to be
> > >   comparable to HIDE_TABLEAM?
> > 
> > Andres, what do you mean by this exactly? It's exactly the same issue:
> > without this, if you change the default compression method, every test
> > that uses \d+ breaks. If you want to be able to run the whole test
> > suite with either compression method and get the same results, you
> > need this. Now, maybe you don't, because perhaps that doesn't seem so
> > important with compression methods as with table AMs.

Arguably, it's more important, since it affects every column in \d+, not just a
"footer" line.

> I think that latter part is why I wasn't sure such an option is
> warranted. Given it's a builtin feature, I didn't really forsee a need
> to be able to run all the tests with a different compression method. And
> it looked a like it could just have been copied from the tableam logic,
> without a clear need. But if it's useful, then ...

This was one of my suggestions and contributions.
I copied it from tableam specifically, not incidentally.
https://www.postgresql.org/message-id/20210214184940.GL1793%40telsasoft.com

-- 
Justin

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.