Horton

Re: backup manifests

David Steele <david@pgmasters.net>

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From: David Steele <david@pgmasters.net>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Andres Freund <andres@anarazel.de>, Amit Kapila <amit.kapila16@gmail.com>, Suraj Kharage <suraj.kharage@enterprisedb.com>, tushar <tushar.ahuja@enterprisedb.com>, Rajkumar Raghuwanshi <rajkumar.raghuwanshi@enterprisedb.com>, Rushabh Lathia <rushabh.lathia@gmail.com>, Tels <nospam-pg-abuse@bloodgate.com>, Andrew Dunstan <andrew.dunstan@2ndquadrant.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>, Jeevan Chalke <jeevan.chalke@enterprisedb.com>, vignesh C <vignesh21@gmail.com>
Date: 2020-03-30T01:05:17Z
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. Try to avoid compiler warnings in optimized builds.

  2. Fix option related issues in pg_verifybackup.

  3. Add index term for backup manifest in documentation.

  4. Code review for backup manifest.

  5. Document the backup manifest file format.

  6. Fix typo in pg_validatebackup documentation.

  7. Exclude backup_manifest file that existed in database, from BASE_BACKUP.

  8. Msys2 tweaks for pg_validatebackup corruption test

  9. Fix resource management bug with replication=database.

  10. Be more careful about time_t vs. pg_time_t in basebackup.c.

  11. pg_validatebackup: Fix 'make clean' to remove tmp_check.

  12. pg_validatebackup: Also use perl2host in TAP tests.

  13. Generate backup manifests for base backups, and validate them.

  14. Add checksum helper functions.

  15. pg_waldump: Add a --quiet option.

  16. Catversion bump for b9b408c48724

  17. pg_basebackup: Refactor code for reading COPY and tar data.

  18. Use a ResourceOwner to track buffer pins in all cases.

  19. Use ARMv8 CRC instructions where available.

  20. Logical replication support for initial data copy

  21. Use Intel SSE 4.2 CRC instructions where available.

  22. Switch to CRC-32C in WAL and other places.

  23. Remove support for 64-bit CRC.

  24. Change CRCs in WAL records from 64bit to 32bit for performance reasons.

On 3/29/20 8:47 PM, Robert Haas wrote:
> On Fri, Mar 27, 2020 at 4:02 PM David Steele <david@pgmasters.net> wrote:
>> I prefer to validate the size and checksum in the same pass, but I'm not
>> sure it's that big a deal.  If the backup is being corrupted under the
>> validate process that would also apply to files that had already been
>> validated.
> 
> I did it like this because I thought that in typical scenarios it
> would be likely to produce useful results more quickly. For instance,
> suppose that you forget to restore the tablespace directories, and
> just get the main $PGDATA directory. Well, if you do it all in one
> pass, you might spend a long time checksumming things before you
> realize that some files are completely missing. I thought it would be
> useful to complain about files that are extra or missing or the wrong
> size FIRST, because that only requires us to stat() each file, and
> only after that do the comparatively extensive checksumming step that
> requires us to read the entire contents of each file. Granted, unless
> you use --exit-on-error, you're going to get all the complaints
> eventually anyway, but you might use that option, or you might hit ^C
> when you start to see a slough of complaints poppoing out.

Yeah, that seems reasonable.

In our case backups are nearly always compressed and/or encrypted so 
even checking the original size is a bit of work. Getting the checksum 
at the same time seems like an obvious win.

Currently we don't have a separate validate command outside of restore 
but when we do we'll consider doing a pass to check for file presence 
(and size when possible) first. Thanks!

> I wasn't worried about
> concurrent modification of the backup because then you're super-hosed
> no matter what.

Really, really, super-hosed.

Regards,
-- 
-David
david@pgmasters.net