Horton

Re: backup manifests

Rushabh Lathia <rushabh.lathia@gmail.com>

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From: Rushabh Lathia <rushabh.lathia@gmail.com>
To: Jeevan Chalke <jeevan.chalke@enterprisedb.com>, Robert Haas <robertmhaas@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@postgresql.org>, vignesh C <vignesh21@gmail.com>, David Steele <david@pgmasters.net>
Date: 2019-11-22T09:57:53Z
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.

Attachments

Thank you Jeevan for reviewing the patch.

On Thu, Nov 21, 2019 at 2:33 PM Jeevan Chalke <
jeevan.chalke@enterprisedb.com> wrote:

>
>
> On Tue, Nov 19, 2019 at 3:30 PM Rushabh Lathia <rushabh.lathia@gmail.com>
> wrote:
>
>>
>>
>> My colleague Suraj did testing and noticed the performance impact
>> with the checksums.   On further testing, he found that specifically with
>> sha its more of performance impact.
>>
>> Please find below statistics:
>>
>> no of tables without checksum SHA256
>> checksum % performnce
>> overhead
>> with
>> SHA-256 md5 checksum % performnce
>> overhead with md5 CRC checksum % performnce
>> overhead with
>> CRC
>> 10 (100 MB
>> in each table) real 0m10.957s
>> user 0m0.367s
>> sys 0m2.275s real 0m16.816s
>> user 0m0.210s
>> sys 0m2.067s 53% real 0m11.895s
>> user 0m0.174s
>> sys 0m1.725s 8% real 0m11.136s
>> user 0m0.365s
>> sys 0m2.298s 2%
>> 20 (100 MB
>> in each table) real 0m20.610s
>> user 0m0.484s
>> sys 0m3.198s real 0m31.745s
>> user 0m0.569s
>> sys 0m4.089s
>> 54% real 0m22.717s
>> user 0m0.638s
>> sys 0m4.026s 10% real 0m21.075s
>> user 0m0.538s
>> sys 0m3.417s 2%
>> 50 (100 MB
>> in each table) real 0m49.143s
>> user 0m1.646s
>> sys 0m8.499s real 1m13.683s
>> user 0m1.305s
>> sys 0m10.541s 50% real 0m51.856s
>> user 0m0.932s
>> sys 0m7.702s 6% real 0m49.689s
>> user 0m1.028s
>> sys 0m6.921s 1%
>> 100 (100 MB
>> in each table) real 1m34.308s
>> user 0m2.265s
>> sys 0m14.717s real 2m22.403s
>> user 0m2.613s
>> sys 0m20.776s 51% real 1m41.524s
>> user 0m2.158s
>> sys 0m15.949s
>> 8% real 1m35.045s
>> user 0m2.061s
>> sys 0m16.308s 1%
>> 100 (1 GB
>> in each table) real 17m18.336s
>> user 0m20.222s
>> sys 3m12.960s real 24m45.942s
>> user 0m26.911s
>> sys 3m33.501s 43% real 17m41.670s
>> user 0m26.506s
>> sys 3m18.402s 2% real 17m22.296s
>> user 0m26.811s
>> sys 3m56.653s
>>
>> sometimes, this test
>> completes within the
>> same time as without
>> checksum. approx. 0.5%
>>
>>
>> Considering the above results, I modified the earlier Robert's patch and
>> added
>> "manifest_with_checksums" option to pg_basebackup.  With a new patch.
>> by default, checksums will be disabled and will be only enabled when
>> "manifest_with_checksums" option is provided.  Also re-based all patch
>> set.
>>
>
> Review comments on 0004:
>
> 1.
> I don't think we need o_manifest_with_checksums variable,
> manifest_with_checksums can be used instead.
>

Yes, done in the latest version of opatch.


> 2.
> We need to document this new option for pg_basebackup and basebackup.
>
>
Done, attaching documentation patch with the mail.

3.
> Also, instead of keeping manifest_with_checksums as a global variable, we
> should pass that to the required function. Patch 0002 already modified the
> signature of all relevant functions anyways. So just need to add one more
> bool
> variable there.
>
>
yes, earlier I did that implementation but later found that we already
have checksum related global variable i.e. noverify_checksums, so
that it will be clean implementation - rather modifying the function
definition
to pass the variable (which is actually global for the operation).

4.
> Why we need a "File" at the start of each entry as we are adding files
> only?
> I wonder if we also need to provide a tablespace name and directory marker
> so
> that we have "Tablespace" and "Dir" at the start.
>

Sorry, I am not quite sure about this, may be Robert is right person
to answer this.


> 5.
> If I don't provide manifest-with-checksums option then too I see that
> checksum
> is calculated for backup_manifest file itself. Is that intentional or
> missed?
> I think we should omit that too if this option is not provided.
>
>
Oops yeah, corrected this in the latest version of patch.

6.
> Is it possible to get only a backup manifest from the server? A client like
> pg_basebackup can then use that to fetch files reading that.
>
>
Currently we don't have any option to just get the manifest file from the
server.  I am not sure but why we need this at this point of time.



Regards,

Rushabh Lathia
www.EnterpriseDB.com