Horton

Re: Custom compression methods

Ildus Kurbangaliev <i.kurbangaliev@postgrespro.ru>

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From: Ildus Kurbangaliev <i.kurbangaliev@postgrespro.ru>
To: Craig Ringer <craig@2ndquadrant.com>
Cc: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>, Andres Freund <andres@anarazel.de>
Date: 2017-11-07T09:44:27Z
Lists: pgsql-hackers 
On Thu, 2 Nov 2017 23:02:34 +0800
Craig Ringer <craig@2ndquadrant.com> wrote:

> On 2 November 2017 at 17:41, Ildus Kurbangaliev
> <i.kurbangaliev@postgrespro.ru> wrote:
> 
> > In this patch compression methods is suitable for MAIN and EXTENDED
> > storages like in current implementation in postgres. Just instead
> > only of LZ4 you can specify any other compression method.  
> 
> We've had this discussion before.
> 
> Please read the "pluggable compression support" thread. See you in a
> few days ;) sorry, it's kinda long.
> 
> https://www.postgresql.org/message-id/flat/20130621000900.GA12425%40alap2.anarazel.de#20130621000900.GA12425@alap2.anarazel.de
> 
> IIRC there were some concerns about what happened with pg_upgrade,
> with consuming precious toast bits, and a few other things.
> 

Thank you for the link, I didn't see that thread when I looked over
mailing lists. I read it briefly, and I can address few things
relating to my patch.

Most concerns have been related with legal issues.
Actually that was the reason I did not include any new compression
algorithms to my patch. Unlike that patch mine only provides syntax
and is just a way to give the users use their own compression algorithms
and deal with any legal issues themselves.

I use only one unused bit in header (there's still one free ;), that's
enough to determine that data is compressed or not.

I did found out that pg_upgrade doesn't work properly with my patch,
soon I will send fix for it.

-- 
---
Ildus Kurbangaliev
Postgres Professional: http://www.postgrespro.com
Russian Postgres Company

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.