Horton

RE: Add LZ4 compression in pg_dump

gkokolatos@pm.me

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From: gkokolatos@pm.me
To: "shiy.fnst@fujitsu.com" <shiy.fnst@fujitsu.com>
Cc: Michael Paquier <michael@paquier.xyz>, Justin Pryzby <pryzby@telsasoft.com>, Tomas Vondra <tomas.vondra@enterprisedb.com>, "pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>, Rachel Heaton <rachelmheaton@gmail.com>
Date: 2023-02-16T11:38:00Z
Lists: pgsql-hackers

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------- Original Message -------
On Wednesday, February 15th, 2023 at 2:51 PM, shiy.fnst@fujitsu.com <shiy.fnst@fujitsu.com> wrote:


> 
> Hi,
> 
> I am interested in this feature and tried the patch. While reading the comments,
> I noticed some minor things that could possibly be improved (in v27-0003 patch).

Thank you very much for the interest. Please find a rebased v28 attached. Due to
the rebase, 0001 of v27 is no longer relevant and has been removed. Your comments
are applied on v28-0002.

> 
> 1.
> + /*
> + * Open a file for writing.
> + *
> + * 'mode' can be one of ''w', 'wb', 'a', and 'ab'. Requrires an already
> + * initialized CompressFileHandle.
> + */
> + int (*open_write_func) (const char *path, const char *mode,
> + CompressFileHandle CFH);
> 
> There is a redundant single quote in front of 'w'.

Fixed.

> 
> 2.
> /
> * Callback function for WriteDataToArchive. Writes one block of (compressed)
> * data to the archive.
> /
> /
> * Callback function for ReadDataFromArchive. To keep things simple, we
> * always read one compressed block at a time.
> */
> 
> Should the function names in the comments be updated?

Agreed. Fixed.

> 
> 3.
> + Assert(strcmp(mode, "r") == 0 || strcmp(mode, "rb") == 0);
> 
> Could we use PG_BINARY_R instead of "r" and "rb" here?

We could and we should. Using PG_BINARY_R has the added benefit
of needing only one strcmp() call. Fixed.

Cheers,
//Georgios

> 
> Regards,
> Shi Yu

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,