Horton

Re: refactoring basebackup.c

Jeevan Ladhe <jeevanladhe.os@gmail.com>

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From: Jeevan Ladhe <jeevanladhe.os@gmail.com>
To: Dipesh Pandit <dipesh.pandit@gmail.com>
Cc: Abhijit Menon-Sen <ams@toroid.org>, Robert Haas <robertmhaas@gmail.com>, Dmitry Dolgov <9erthalion6@gmail.com>, Jeevan Ladhe <jeevan.ladhe@enterprisedb.com>, Mark Dilger <mark.dilger@enterprisedb.com>, pgsql-hackers@postgresql.org, tushar <tushar.ahuja@enterprisedb.com>
Date: 2022-02-10T14:31:50Z
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.

Thanks for the patch, Dipesh.
With a quick look at the patch I have following observations:

----------------------------------------------------------
In bbstreamer_lz4_compressor_new(), I think this alignment is not needed
on client side:

    /* Align the output buffer length. */
    compressed_bound += compressed_bound + BLCKSZ - (compressed_bound %
BLCKSZ);
----------------------------------------------------------

bbstreamer_lz4_compressor_content(), avail_in and len variables both are
not changed. I think we can simply change the len to avail_in in the
argument list.
----------------------------------------------------------

Comment:
+        * Update the offset and capacity of output buffer based on based
on number
+        * of bytes written to output buffer.

I think it is thinko:

+        * Update the offset and capacity of output buffer based on number
of
+        * bytes written to output buffer.
----------------------------------------------------------

Indentation:

+       if ((mystreamer->base.bbs_buffer.maxlen -
mystreamer->bytes_written) <=
+                       footer_bound)

----------------------------------------------------------
I think similar to bbstreamer_lz4_compressor_content() in
bbstreamer_lz4_decompressor_content() we can change len to avail_in.


Regards,
Jeevan Ladhe

On Thu, 10 Feb 2022 at 18:11, Dipesh Pandit <dipesh.pandit@gmail.com> wrote:

> Hi,
>
> > On Mon, Jan 31, 2022 at 4:41 PM Jeevan Ladhe <
> jeevan.ladhe@enterprisedb.com> wrote:
>
>> Hi Robert,
>>
>> I had an offline discussion with Dipesh, and he will be working on the
>> lz4 client side decompression part.
>>
>
> Please find the attached patch to support client side compression
> and decompression using lz4.
>
> Added a new lz4 bbstreamer to compress the archive chunks at
> client if user has specified --compress=clinet-lz4:[LEVEL] option
> in pg_basebackup. The new streamer accepts archive chunks
> compresses it and forwards it to plain-writer.
>
> Similarly, If a user has specified a server compressed lz4 archive
> with plain format (-F p) backup then it requires decompressing
> the compressed archive chunks before forwarding it to tar extractor.
> Added a new bbstreamer to decompress the compressed archive
> and forward it to tar extractor.
>
> Note: This patch can be applied on Jeevan Ladhe's v12 patch
> for lz4 compression.
>
> Thanks,
> Dipesh
>