Horton

Re: [HACKERS] Custom compression methods

Dilip Kumar <dilipbalaut@gmail.com>

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From: Dilip Kumar <dilipbalaut@gmail.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Alvaro Herrera <alvherre@alvh.no-ip.org>, Andres Freund <andres@anarazel.de>, Justin Pryzby <pryzby@telsasoft.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>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2021-03-20T08:05:52Z
Lists: pgsql-hackers 
On Sat, Mar 20, 2021 at 1:22 PM Dilip Kumar <dilipbalaut@gmail.com> wrote:
>
> On Sat, Mar 20, 2021 at 8:11 AM Robert Haas <robertmhaas@gmail.com> wrote:
> >
> > On Fri, Mar 19, 2021 at 8:25 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> > > Extrapolating from the way we've dealt with similar issues
> > > in the past, I think the structure of pg_dump's output ought to be:
> > >
> > > 1. SET default_toast_compression = 'source system's value'
> > > in among the existing passel of SETs at the top.  Doesn't
> > > matter whether or not that is the compiled-in value.
> > >
> > > 2. No mention of compression in any CREATE TABLE command.
> > >
> > > 3. For any column having a compression option different from
> > > the default, emit ALTER TABLE SET ... to set that option after
> > > the CREATE TABLE.  (You did implement such a SET, I trust.)
> >
> > Actually, *I* didn't implement any of this. But ALTER TABLE sometab
> > ALTER somecol SET COMPRESSION somealgo works.
> >
> > This sounds like a reasonable approach.
>
> The attached patch implements that.

After sending this, just saw Justin also included patches for this.  I
think the ALTER ..SET COMPRESSION is more or less similar, I just
fetched it from the older version of the patch set.  But SET
default_toast_compression are slightly different.  I will look into
your version and provide my opinion on which one looks better and we
can commit that and feel free to share your thoughts.

-- 
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com

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.