Re: backup manifests

Andres Freund <andres@anarazel.de>

From: Andres Freund <andres@anarazel.de>
To: Robert Haas <robertmhaas@gmail.com>
Cc: David Steele <david@pgmasters.net>, Noah Misch <noah@leadboat.com>, Stephen Frost <sfrost@snowman.net>, 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: 2020-03-30T21:08:01Z
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.

Hi,

On 2020-03-30 15:23:08 -0400, Robert Haas wrote:
> On Mon, Mar 30, 2020 at 2:59 PM Andres Freund <andres@anarazel.de> wrote:
> > I wonder if it'd not be best, independent of whether we build in this
> > verification, to include that metadata in the manifest file. That's for
> > sure better than having to build a separate tool to parse timeline
> > history files.
> 
> I don't think that's better, or at least not "for sure better". The
> backup_label going to include the START TIMELINE, and if -Xfetch is
> used, we're also going to have all the timeline history files. If the
> backup manifest includes those same pieces of information, then we've
> got two sources of truth: one copy in the files the server's actually
> going to read, and another copy in the backup_manifest which we're
> going to potentially use for validation but ignore at runtime. That
> seems not great.

The data in the backup label isn't sufficient though. Without having
parsed the timeline file there's no way to verify that the correct WAL
is present. I guess we can also add client side tools to parse
timelines, add command the fetch all of the required files, and then
interpret that somehow.

But that seems much more complicated.

Imo it makes sense to want to be able verify that WAL looks correct even
transporting WAL using another method (say archiving) and thus using
pg_basebackup's -Xnone.

For the manifest to actually list what's required for the base backup
doesn't seem redundant to me. Imo it makes the manifest file make a good
bit more sense, since afterwards it actually describes the whole base
backup.

Taking the redundancy agreement a bit further you can argue that we
don't need a list of relation files at all, since they're in the catalog
:P. Obviously going to that extreme doesn't make all that much
sense... But I do think it's a second source of truth that's independent
of what the backends actually are going to read.

Greetings,

Andres Freund