Horton

Re: refactoring basebackup.c

Abhijit Menon-Sen <ams@toroid.org>

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From: Abhijit Menon-Sen <ams@toroid.org>
To: Robert Haas <robertmhaas@gmail.com>
Cc: 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: 2022-02-09T13:41:27Z
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.

At 2022-02-02 10:55:53 -0500, robertmhaas@gmail.com wrote:
>
> On Tue, Jan 18, 2022 at 1:55 PM Robert Haas <robertmhaas@gmail.com> wrote:
> > 0001 adds "server" and "blackhole" as backup targets. It now has some
> > tests. This might be more or less ready to ship, unless somebody else
> > sees a problem, or I find one.
> 
> I played around with this a bit and it seems quite easy to extend this
> further. So please find attached a couple more patches to generalize
> this mechanism.

It took me a while to assimilate these patches, including the backup
targets one, which I hadn't looked at before. Now that I've wrapped my
head around how to put the pieces together, I really like the idea. As
you say, writing non-trivial integrations in C will take some effort,
but it seems worthwhile. It's also nice that one can continue to use
pg_basebackup to trigger the backups and see progress information.

> Granted, coding up a new base backup target is
> something only experienced C hackers are likely to do, but the fact
> that I was able to throw this together so quickly suggests to me that
> I've got the design basically right, and that anyone who does want to
> plug into the new mechanism shouldn't have too much trouble doing so.
> 
> Thoughts?

Yes, it looks simple to follow the example set by basebackup_to_shell to
write a custom target. The complexity will be in whatever we need to do
to store/forward the backup data, rather than in obtaining the data in
the first place, which is exactly as it should be.

Thanks!

-- Abhijit