Horton

Re: Add LZ4 compression in pg_dump

Tomas Vondra <tomas.vondra@enterprisedb.com>

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From: Tomas Vondra <tomas.vondra@enterprisedb.com>
To: gkokolatos@pm.me
Cc: Justin Pryzby <pryzby@telsasoft.com>, Alexander Lakhin <exclusion@gmail.com>, shiy.fnst@fujitsu.com, Michael Paquier <michael@paquier.xyz>, pgsql-hackers@lists.postgresql.org, Rachel Heaton <rachelmheaton@gmail.com>
Date: 2023-03-28T22:02:00Z
Lists: pgsql-hackers 
On 3/28/23 18:07, gkokolatos@pm.me wrote:
> 
> ------- Original Message -------
> On Friday, March 24th, 2023 at 10:30 AM, gkokolatos@pm.me <gkokolatos@pm.me> wrote:
> 
>>
>> ------- Original Message -------
>> On Thursday, March 23rd, 2023 at 6:10 PM, Tomas Vondra tomas.vondra@enterprisedb.com wrote:
>>
>>> This leaves the empty-data issue (which we have a fix for) and the
>>> switch to LZ4F. And then the zstd part.
>>
>> Please expect promptly a patch for the switch to frames.
> 
> Please find the expected patch attached. Note that the bulk of the
> patch is code unification, variable renaming to something more
> appropriate, and comment addition. These are changes that are not
> strictly necessary to switch to LZ4F. I do believe that are
> essential for code hygiene after the switch and they do belong
> on the same commit. 
> 


I think the patch is fine, but I'm wondering if the renames shouldn't go
a bit further. It removes references to LZ4File struct, but there's a
bunch of functions with LZ4File_ prefix. Why not to simply use LZ4_
prefix? We don't have GzipFile either.

Sure, it might be a bit confusing because lz4.h uses LZ4_ prefix, but
then we probably should not define LZ4_compressor_init ...

Also, maybe the comments shouldn't use "File API" when compress_io.c
calls that "Compressed stream API".


regards

-- 
Tomas Vondra
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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,