Re: [HACKERS] Custom compression methods

Dilip Kumar <dilipbalaut@gmail.com>

From: Dilip Kumar <dilipbalaut@gmail.com>
To: Justin Pryzby <pryzby@telsasoft.com>
Cc: Robert Haas <robertmhaas@gmail.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: 2021-03-15T12:14:33Z
Lists: pgsql-hackers

Attachments

On Fri, Mar 12, 2021 at 4:06 PM Justin Pryzby <pryzby@telsasoft.com> wrote:
>
> I think these names need to be more specific.
>
> +typedef enum CompressionId
> +{
> +        PGLZ_COMPRESSION_ID = 0,
> +        LZ4_COMPRESSION_ID = 1
> +
>
> CompressionId, PGLZ_COMPRESSION_ID, LZ4_COMPRESSION_ID are also being used by
> Andrey's WAL compression patch.  I suggested he use a prefix, but your patch is
> also of limited scope (TOAST).


In the attached patches I have changed this, other than this I have
run pg_indent on all the patches and now CTAS and Matview will compare
the compression method with the target attribute and it will
recompress if required.  CLUSTER, VACUUM
FULL(reform_and_rewrite_tuple) and ATRewriteTable will also recompress
as per the target attribute.  But the changes of
reform_and_rewrite_tuple and ATRewriteTable are in patch 0005, because
now whenever we are moving to target table we are always recompress so
there is no use-case to recompress in reform_and_rewrite_tuple and
ATRewriteTable unless we provide an option to alter the attribute
compression.  Basically, we are allowed to change the attribute
compression without any rewrite but on the very next opportunity when
the table is getting rewritten the data will be recompressed based on
the current compression method.  Also done some improvement and
comment changes in patch 0002 and patch 0006.

-- 
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.