Horton

Re: [HACKERS] Custom compression methods

Dilip Kumar <dilipbalaut@gmail.com>

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From: Dilip Kumar <dilipbalaut@gmail.com>
To: Justin Pryzby <pryzby@telsasoft.com>
Cc: Jaime Casanova <jcasanov@systemguards.com.ec>, Robert Haas <robertmhaas@gmail.com>, Andres Freund <andres@anarazel.de>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, David Steele <david@pgmasters.net>, Ildus Kurbangaliev <i.kurbangaliev@gmail.com>, Dmitry Dolgov <9erthalion6@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2021-03-24T10:10:58Z
Lists: pgsql-hackers

Attachments

On Wed, Mar 24, 2021 at 3:10 PM Dilip Kumar <dilipbalaut@gmail.com> wrote:
>
> On Wed, Mar 24, 2021 at 2:49 PM Justin Pryzby <pryzby@telsasoft.com> wrote:
> >
> > On Wed, Mar 24, 2021 at 02:24:41PM +0530, Dilip Kumar wrote:
> > > On Wed, Mar 24, 2021 at 1:43 PM Dilip Kumar <dilipbalaut@gmail.com> wrote:
> > > > > create table t1 (col1 text, col2 text);
> > > > > create unique index on t1 ((col1 || col2));
> > > > > insert into t1 values((select array_agg(md5(g::text))::text from
> > > > > generate_series(1, 256) g), version());
> > > > >
> > > > > Attached is a backtrace from current HEAD
> > > >
> > > > Thanks for reporting this issue.  Actually, I missed setting the
> > > > attcompression for the expression index and that is causing this
> > > > assert.  I will send a patch in some time.
> > >
> > > PFA, patch to fix the issue.
> >
> > Could you include a test case exercizing this code path ?
> > Like Jaime's reproducer.
>
> I will do that.

0001 ->shows compression method for the index attribute in index describe
0002 -> fix the reported bug (test case included)

Apart from this, I was thinking that currently, we are allowing to
ALTER SET COMPRESSION only for the table and matview,  IMHO it makes
sense to allow to alter the compression method for the index column as
well?  I mean it is just a one-line change, but just wanted to know
the opinion from others.  It is not required for the storage because
indexes can not have a toast table but index attributes can be
compressed so it makes sense to allow to alter the compression method.
Thought?


--
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.