Horton

Re: Add LZ4 compression in pg_dump

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Justin Pryzby <pryzby@telsasoft.com>
Cc: Georgios <gkokolatos@protonmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Rachel Heaton <rachelmheaton@gmail.com>
Date: 2022-03-28T12:36:15Z
Lists: pgsql-hackers 
On Sun, Mar 27, 2022 at 12:06 PM Justin Pryzby <pryzby@telsasoft.com> wrote:
> Maybe it should take an argument which specifies the default algorithm to use
> for input of a numeric "level".  And reject such input if not specified, since
> wal_compression has never taken a "level", so it's not useful or desirable to
> have that default to some new algorithm.

That sounds odd to me. Wouldn't it be rather confusing if a bare
integer meant gzip for one case and lz4 for another?

> I could write this down if you want, although I'm not sure how/if you intend
> other people to use bc_algorithm and bc_algorithm.  I don't think it's
> important to do for v15, but it seems like it could be done after featue
> freeze.  pg_dump+lz4 is targetting v16, although there's a cleanup patch that
> could also go in before branching.

Well, I think the first thing we should do is get rid of enum
WalCompressionMethod and use enum WalCompression instead. They've got
the same elements and very similar names, but the WalCompressionMethod
ones just have names like COMPRESSION_NONE, which is too generic,
whereas WalCompressionMethod uses WAL_COMPRESSION_NONE, which is
better. Then I think we should also rename the COMPR_ALG_* constants
in pg_dump.h to names like DUMP_COMPRESSION_*. Once we do that we've
got rid of all the unprefixed things that purport to be a list of
compression algorithms.

Then, if people are willing to adopt the syntax that the
backup_compression.c/h stuff supports as a project standard (+1 from
me) we can go the other way and rename that stuff to be more generic,
taking backup out of the name.

-- 
Robert Haas
EDB: http://www.enterprisedb.com

Commits

  1. Advance input pointer when LZ4 compressing data

  2. Null-terminate the output buffer of LZ4Stream_gets

  3. Rework code defining default compression for dir/custom formats in pg_dump

  4. pg_dump: Use only LZ4 frame format for compression

  5. Minor comment improvements for compress_lz4

  6. Unify buffer sizes in pg_dump compression API

  7. Improve type handling in pg_dump's compress file API

  8. Improve wording in pg_dump compression docs

  9. Fix condition in pg_dump TAP test

  10. Add LZ4 compression to pg_dump

  11. Introduce a generic pg_dump compression API

  12. Prepare pg_dump internals for additional compression methods

  13. Fix behavior with pg_restore -l and compressed dumps

  14. Add 250c8ee07ed to git-blame-ignore-revs

  15. Provide test coverage in pg_dump for default behaviors with compression

  16. Switch pg_dump to use compression specifications

  17. Refactor code parsing compression option values (-Z/--compress)

  18. meson: Add some missing env settings for tests of pg_dump and pg_verifybackup

  19. Extend TAP tests of pg_dump to test for compression with gzip

  20. Clean up some dead code in pg_dump with tar format and gzip compression

  21. Add TAP test in pg_dump with --format=tar and --compress

  22. Replace BASE_BACKUP COMPRESSION_LEVEL option with COMPRESSION_DETAIL.

  23. Refactor the pg_dump zlib code from pg_backup_custom.c to a separate file,