Horton

Re: [HACKERS] Custom compression methods

Ildus Kurbangaliev <i.kurbangaliev@postgrespro.ru>

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From: Ildus Kurbangaliev <i.kurbangaliev@postgrespro.ru>
To: Ildar Musin <i.musin@postgrespro.ru>
Cc: Robert Haas <robertmhaas@gmail.com>, Alexander Korotkov <a.korotkov@postgrespro.ru>, 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>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>, Chapman Flack <chap@anastigmatix.net>
Date: 2018-01-25T14:24:57Z
Lists: pgsql-hackers

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On Thu, 25 Jan 2018 16:03:20 +0300
Ildar Musin <i.musin@postgrespro.ru> wrote:

Thanks for review!

> 
> As you see, compression option is copied anyway. I suggest adding new 
> INCLUDING COMPRESSION option to enable user to explicitly specify 
> whether they want or not to copy compression settings.

Good catch, i missed INCLUDE options for LIKE command. Added INCLUDING
COMPRESSION as you suggested.

> 
> 
> I found a few phrases in documentation that can be improved. But the 
> documentation should be checked by a native speaker.
> 
> In compression-am.sgml:
> "an compression access method" -> "a compression access method"
> "compression method method" -> "compression method"
> "compability" -> "compatibility"
> Probably "local-backend cached state" would be better to replace with 
> "per backend cached state"?
> "Useful to store the parsed view of the compression options" -> "It 
> could be useful for example to cache compression options"
> "and stores result of" -> "and stores the result of"
> "Called when CompressionAmOptions is creating." -> "Called when 
> <structname>CompressionAmOptions</structname> is being initialized"
> 
> "Note that in any system cache invalidation related with 
> pg_attr_compression relation the options will be cleaned" -> "Note
> that any <literal>pg_attr_compression</literal> relation invalidation
> will cause all the cached <literal>acstate</literal> options cleared."
> "Function used to ..." -> "Function is used to ..."
> 
> I think it would be nice to mention custom compression methods in 
> storage.sgml. At this moment it only mentions built-in pglz
> compression.
> 

I agree, the documentation would require a native speaker. Fixed the
lines you mentioned.

-- 
---
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.