Horton

Re: Add LZ4 compression in pg_dump

Justin Pryzby <pryzby@telsasoft.com>

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From: Justin Pryzby <pryzby@telsasoft.com>
To: gkokolatos@pm.me
Cc: Michael Paquier <michael@paquier.xyz>, pgsql-hackers@lists.postgresql.org, Rachel Heaton <rachelmheaton@gmail.com>
Date: 2022-12-17T23:26:15Z
Lists: pgsql-hackers 
001: still refers to "gzip", which is correct for -Fp and -Fd but not
for -Fc, for which it's more correct to say "zlib".  That affects the
name of the function, structures, comments, etc.  I'm not sure if it's
an issue to re-use the basebackup compression routines here.  Maybe we
should accept "-Zn" for zlib output (-Fc), but reject "gzip:9", which
I'm sure some will find confusing, as it does not output.  Maybe 001
should be split into a patch to re-use the existing "cfp" interface
(which is a clear win), and 002 to re-use the basebackup interfaces for
user input and constants, etc.

001 still doesn't compile on freebsd, and 002 doesn't compile on
windows.  Have you checked test results from cirrusci on your private
github account ?

002 says:
+       save_errno = errno;                                                                                                                                                                                 
+       errno = save_errno;                                                                                                                                                                                 

I suppose that's intended to wrap the preceding library call.

002 breaks "pg_dump -Fc -Z2" because (I think) AllocateCompressor()
doesn't store the passed-in compression_spec.

003 still uses <lz4.h> and not "lz4.h".

Earlier this year I also suggested to include an 999 patch to change to
use LZ4 as the default compression, to exercise the new code under CI.
I suggest to re-open the cf patch entry after that passes tests on all
platforms and when it's ready for more review.

BTW, some of these review comments are the same as what I sent earlier
this year.

https://www.postgresql.org/message-id/20220326162156.GI28503%40telsasoft.com
https://www.postgresql.org/message-id/20220705151328.GQ13040%40telsasoft.com

-- 
Justin

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,