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: gkokolatos@pm.me, pgsql-hackers@lists.postgresql.org, Rachel Heaton <rachelmheaton@gmail.com>
Date: 2022-12-19T04:06:00Z
Lists: pgsql-hackers 
On Sat, Dec 17, 2022 at 05:26:15PM -0600, Justin Pryzby wrote:
> 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".

Or should we begin by changing all these existing "not built with zlib 
support" error strings to the more generic "this build does not
support compression with %s" to reduce the number of messages to
translate?  That would bring consistency with the other tools dealing
with compression.

> 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 ?

FYI, I have re-added an entry to the CF app to get some automated
coverage:
https://commitfest.postgresql.org/41/3571/

On MinGW, a complain about the open() callback, which I guess ought to
be avoided with a rename:
[00:16:37.254] compress_gzip.c:356:38: error: macro "open" passed 4 arguments, but takes just 3
[00:16:37.254]   356 |  ret = CFH->open(fname, -1, mode, CFH);
[00:16:37.254]       |                                      ^
[00:16:37.254] In file included from ../../../src/include/c.h:1309,
[00:16:37.254]                  from ../../../src/include/postgres_fe.h:25,
[00:16:37.254]                  from compress_gzip.c:15:

On MSVC, some declaration conflicts, for a similar issue:
[00:12:31.966] ../src/bin/pg_dump/compress_io.c(193): error C2371: '_read': redefinition; different basic types
[00:12:31.966] C:\Program Files (x86)\Windows Kits\10\include\10.0.20348.0\ucrt\corecrt_io.h(252): note: see declaration of '_read'
[00:12:31.966] ../src/bin/pg_dump/compress_io.c(210): error C2371: '_write': redefinition; different basic types
[00:12:31.966] C:\Program Files (x86)\Windows Kits\10\include\10.0.20348.0\ucrt\corecrt_io.h(294): note: see declaration of '_write'

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

Hmm.  This looks like a gap in the existing tests that we'd better fix
first.  This CI is green on Linux.

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

This should be <lz4.h>, not "lz4.h".
--
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,