Horton

Re: [HACKERS] Custom compression methods

Alexander Korotkov <a.korotkov@postgrespro.ru>

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From: Alexander Korotkov <a.korotkov@postgrespro.ru>
To: "i.kurbangaliev" <i.kurbangaliev@postgrespro.ru>
Cc: konstantin knizhnik <k.knizhnik@postgrespro.ru>, Ildar Musin <i.musin@postgrespro.ru>, Robert Haas <robertmhaas@gmail.com>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, Alvaro Herrera <alvherre@2ndquadrant.com>, Евгений Шишкин <itparanoia@gmail.com>, Andres Freund <andres@anarazel.de>, Oleg Bartunov <obartunov@gmail.com>, Craig Ringer <craig@2ndquadrant.com>, Peter Eisentraut <peter.eisentraut@2ndquadrant.com>, pgsql-hackers <pgsql-hackers@postgresql.org>, Chapman Flack <chap@anastigmatix.net>
Date: 2018-07-23T13:16:19Z
Lists: pgsql-hackers 
Hi!

On Mon, Jul 2, 2018 at 3:56 PM Ildus Kurbangaliev
<i.kurbangaliev@postgrespro.ru> wrote:
> On Mon, 18 Jun 2018 17:30:45 +0300
> Ildus Kurbangaliev <i.kurbangaliev@postgrespro.ru> wrote:
>
> > On Tue, 24 Apr 2018 14:05:20 +0300
> > Alexander Korotkov <a.korotkov@postgrespro.ru> wrote:
> >
> > >
> > > Yes, this patch definitely lacks of good usage example.  That may
> > > lead to some misunderstanding of its purpose.  Good use-cases
> > > should be shown before we can consider committing this.  I think
> > > Ildus should try to implement at least custom dictionary compression
> > > method where dictionary is specified by user in parameters.
> > >
> >
> > Hi,
> >
> > attached v16 of the patch. I have splitted the patch to 8 parts so now
> > it should be easier to make a review. The main improvement is zlib
> > compression method with dictionary support like you mentioned. My
> > synthetic tests showed that zlib gives more compression but usually
> > slower than pglz.
> >
>
> I have noticed that my patch is failing to apply on cputube. Attached a
> rebased version of the patch. Nothing have really changed, just added
> and fixed some tests for zlib and improved documentation.

I'm going to review this patch.  Could you please rebase it?  It
doesn't apply for me due to changes made in src/bin/psql/describe.c.

patching file src/bin/psql/describe.c
Hunk #1 FAILED at 1755.
Hunk #2 FAILED at 1887.
Hunk #3 FAILED at 1989.
Hunk #4 FAILED at 2019.
Hunk #5 FAILED at 2030.
5 out of 5 hunks FAILED -- saving rejects to file src/bin/psql/describe.c.rej

Also, please not that PostgreSQL 11 already passed feature freeze some
time ago.  So, please adjust your patch to expect PostgreSQL 12 in the
lines like this:

+ if (pset.sversion >= 110000)

------
Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
The 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.