Horton

Re: [HACKERS] Custom compression methods

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Tomas Vondra <tomas.vondra@2ndquadrant.com>, Ildus Kurbangaliev <i.kurbangaliev@postgrespro.ru>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>, Ildar Musin <i.musin@postgrespro.ru>
Date: 2017-12-01T21:52:17Z
Lists: pgsql-hackers 
On 2017-12-01 16:14:58 -0500, Robert Haas wrote:
> Honestly, if we can give everybody a 4% space reduction by switching
> to lz4, I think that's totally worth doing -- but let's not make
> people choose it, let's make it the default going forward, and keep
> pglz support around so we don't break pg_upgrade compatibility (and so
> people can continue to choose it if for some reason it works better in
> their use case).  That kind of improvement is nothing special in a
> specific workload, but TOAST is a pretty general-purpose mechanism.  I
> have become, through a few bitter experiences, a strong believer in
> the value of trying to reduce our on-disk footprint, and knocking 4%
> off the size of every TOAST table in the world does not sound
> worthless to me -- even though context-aware compression can doubtless
> do a lot better.

+1. It's also a lot faster, and I've seen way way to many workloads with
50%+ time spent in pglz.

Greetings,

Andres Freund

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.