Re: documenting the backup manifest file format

Fujii Masao <masao.fujii@oss.nttdata.com>

From: Fujii Masao <masao.fujii@oss.nttdata.com>
To: Andrew Dunstan <andrew.dunstan@2ndquadrant.com>, Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: David Steele <david@pgmasters.net>, Robert Haas <robertmhaas@gmail.com>, Justin Pryzby <pryzby@telsasoft.com>, 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>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>, Jeevan Chalke <jeevan.chalke@enterprisedb.com>, vignesh C <vignesh21@gmail.com>
Date: 2020-05-15T06:10:38Z
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 2020/04/15 5:33, Andrew Dunstan wrote:
> 
> On 4/14/20 4:09 PM, Alvaro Herrera wrote:
>> On 2020-Apr-14, Andrew Dunstan wrote:
>>
>>> OK, but I think if we're putting a timestamp string in ISO-8601 format
>>> in the manifest it should be in UTC / Zulu time, precisely to avoid
>>> these issues. If that's too much trouble then yes an epoch time will
>>> probably do.
>> The timestamp is always specified and always UTC (except the code calls
>> it GMT).
>>
>> +   /*
>> +    * Convert last modification time to a string and append it to the
>> +    * manifest. Since it's not clear what time zone to use and since time
>> +    * zone definitions can change, possibly causing confusion, use GMT
>> +    * always.
>> +    */
>> +   appendStringInfoString(&buf, "\"Last-Modified\": \"");
>> +   enlargeStringInfo(&buf, 128);
>> +   buf.len += pg_strftime(&buf.data[buf.len], 128, "%Y-%m-%d %H:%M:%S %Z",
>> +                          pg_gmtime(&mtime));
>> +   appendStringInfoString(&buf, "\"");
>>
>> I was merely saying that it's trivial to make this iso-8601 compliant as
>>
>>      buf.len += pg_strftime(&buf.data[buf.len], 128, "%Y-%m-%dT%H:%M:%SZ",
>>
>> ie. omit the "GMT" string and replace it with a literal Z, and remove
>> the space and replace it with a T.

I have one question related to this; Why don't we use log_timezone,
like backup_label? log_timezone is used for "START TIME" field in
backup_label. Sorry if this was already discussed.

		/* Use the log timezone here, not the session timezone */
		stamp_time = (pg_time_t) time(NULL);
		pg_strftime(strfbuf, sizeof(strfbuf),
					"%Y-%m-%d %H:%M:%S %Z",
					pg_localtime(&stamp_time, log_timezone));

OTOH, *if* we want to use the same timezone for backup-related files because
backup can be used in different environements and timezone setting
may be different there or for other reasons, backup_label also should use
GMT or something for the sake of consistency?

Regards,

-- 
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION