Horton

Re: Add LZ4 compression in pg_dump

Michael Paquier <michael@paquier.xyz>

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From: Michael Paquier <michael@paquier.xyz>
To: Justin Pryzby <pryzby@telsasoft.com>
Cc: Tomas Vondra <tomas.vondra@enterprisedb.com>, gkokolatos@pm.me, shiy.fnst@fujitsu.com, pgsql-hackers@lists.postgresql.org, Rachel Heaton <rachelmheaton@gmail.com>
Date: 2023-04-25T06:02:18Z
Lists: pgsql-hackers

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On Wed, Apr 12, 2023 at 07:53:53PM -0500, Justin Pryzby wrote:
> I doubt it - in the !HAVE_LIBZ case, it's currently an "if" statement
> with nothing but a comment, which isn't a problem.
> 
> I think the only issue with an empty "if" is when you have no braces,
> like:
> 
> 	if (...)
> #if ...
> 		something;
> #endif
> 
> 	// problem here //

(My apologies for the late reply.)

Still it could be easily messed up, and that's not a style that
really exists in the tree, either, because there are always #else
blocks set up in such cases.  Another part that makes me a bit
uncomfortable is that we would still call twice
parse_compress_specification(), something that should not happen but
we are doing so on HEAD because the default compression_algorithm_str
is "none" and we want to enforce "gzip" for custom and directory
formats when building with zlib.

What about just moving this block a bit up, just before the
compression spec parsing, then?  If we set compression_algorithm_str,
the specification is compiled with the expected default, once instead
of twice.
--
Michael

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,