Horton

Re: refactoring basebackup.c

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Jeevan Ladhe <jeevan.ladhe@enterprisedb.com>
Cc: Dilip Kumar <dilipbalaut@gmail.com>, Mark Dilger <mark.dilger@enterprisedb.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>, tushar <tushar.ahuja@enterprisedb.com>
Date: 2021-09-21T17:20:04Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Document BaseBackupSync and BaseBackupWrite wait events.

  2. Support long distance matching for zstd compression

  3. Fix possible NULL-pointer-deference in backup_compression.c.

  4. Allow parallel zstd compression when taking a base backup.

  5. Make PostgreSQL::Test::Cluster::run_log() return a useful value.

  6. Fix a few goofs in new backup compression code.

  7. Replace BASE_BACKUP COMPRESSION_LEVEL option with COMPRESSION_DETAIL.

  8. Add 'basebackup_to_shell' contrib module.

  9. Allow extensions to add new backup targets.

  10. Change HAVE_LIBLZ4 and HAVE_LIBZSTD tests to USE_LZ4 and USE_ZSTD.

  11. pg_basebackup: Clean up some bogus file extension tests.

  12. pg_basebackup: Avoid unclean failure with server-compression and -D -.

  13. Fix LZ4 tests for remaining buffer space.

  14. Add support for zstd base backup compression.

  15. pg_basebackup: Allow client-side LZ4 (de)compression.

  16. Add suport for server-side LZ4 base backup compression.

  17. Add min() and max() aggregates for xid8.

  18. Remove superfluous variable.

  19. pg_basebackup: Cleaner handling when compression is multiply specified.

  20. Allow server-side compression to be used with -Fp.

  21. pg_basebackup: Fix a couple of recently-introduced bugs.

  22. Tidy up a few cosmetic issues related to pg_basebackup.

  23. Server-side gzip compression.

  24. Unbreak pg_basebackup/t/010_pg_basebackup.pl on msys

  25. Suppress variable-set-but-not-used warning from clang 13.

  26. Extend the options of pg_basebackup to control compression

  27. Support base backup targets.

  28. Modify pg_basebackup to use a new COPY subprotocol for base backups.

  29. Document that tar archives are now properly terminated.

  30. Fix thinko in bbsink_throttle_manifest_contents.

  31. Have the server properly terminate tar archives.

  32. Minimal fix for unterminated tar archive problem.

  33. Introduce 'bbstreamer' abstraction to modularize pg_basebackup.

  34. Introduce 'bbsink' abstraction to modularize base backup code.

  35. Refactor basebackup.c's _tarWriteDir() function.

  36. Flexible options for CREATE_REPLICATION_SLOT.

  37. Flexible options for BASE_BACKUP.

On Tue, Sep 21, 2021 at 9:35 AM Jeevan Ladhe
<jeevan.ladhe@enterprisedb.com> wrote:
> Here is a patch for lz4 based on the v5 set of patches. The patch adapts with the
> bbsink changes, and is now able to make the provision for the required length
> for the output buffer using the new callback function bbsink_lz4_begin_backup().
>
> Sample command to take backup:
> pg_basebackup -t server:/tmp/data_lz4 -Xnone --server-compression=lz4
>
> Please let me know your thoughts.

This pretty much looks right, with the exception of the autoFlush
thing about which I sent a separate email. I need to write docs for
all of this, and ideally test cases. It might also be good if
pg_basebackup had an option to un-gzip or un-lz4 archives, but I
haven't thought too hard about what would be required to make that
work.

+ if (opt->compression == BACKUP_COMPRESSION_LZ4)

else if

+ /* First of all write the frame header to destination buffer. */
+ Assert(CHUNK_SIZE >= LZ4F_HEADER_SIZE_MAX);
+ headerSize = LZ4F_compressBegin(mysink->ctx,
+ mysink->base.bbs_next->bbs_buffer,
+ CHUNK_SIZE,
+ prefs);

I think this is wrong. I think you should be passing bbs_buffer_length
instead of CHUNK_SIZE, and I think you can just delete CHUNK_SIZE. If
you think otherwise, why?

+ * sink's bbs_buffer of length that can accomodate the compressed input

Spelling.

+ * Make it next multiple of BLCKSZ since the buffer length is expected so.

The buffer length is expected to be a multiple of BLCKSZ, so round up.

+ * If we are falling short of available bytes needed by
+ * LZ4F_compressUpdate() per the upper bound that is decided by
+ * LZ4F_compressBound(), send the archived contents to the next sink to
+ * process it further.

If the number of available bytes has fallen below the value computed
by LZ4F_compressBound(), ask the next sink to process the data so that
we can empty the buffer.

-- 
Robert Haas
EDB: http://www.enterprisedb.com