How to get accurate backup end time when it is taken from synchronous standby ? - Mailing list pgsql-hackers

From Harinath Kanchu
Subject How to get accurate backup end time when it is taken from synchronous standby ?
Date
Msg-id A35BF838-C950-488F-8AD1-CA5DAA7BA6E1@apple.com
Whole thread Raw
Responses Re: How to get accurate backup end time when it is taken from synchronous standby ?
List pgsql-hackers
Greetings,


When we take backups from a synchronous standby replica, how can we get the accurate timestamp of the backup end time ? (As backup history files are not generated on standbys)For example:
this is a part of control file after a backup (created using wal-g by calling pg_startbackup and pg_stopbackup),
Fake LSN counter for unlogged rels:   0/3E8
Minimum recovery ending location:     28/28000B68
Min recovery ending loc's timeline:   2
Backup start location:                0/0
Backup end location:                  0/0
End-of-backup record required:        no
here I can see that minimum recovery ending location as LSN value, how can we get the timestamp of it ?The backup label file looks like this.
INFO: 2022/07/26 23:25:23.850621 ------------ LABLE FILE START ----------
INFO: 2022/07/26 23:25:23.850628 START WAL LOCATION: 1D/F94C7320 (file 000000020000001D000000F9)
INFO: 2022/07/26 23:25:23.850633 CHECKPOINT LOCATION: 1E/EDA8700
INFO: 2022/07/26 23:25:23.850639 BACKUP METHOD: streamed
INFO: 2022/07/26 23:25:23.850645 BACKUP FROM: standby
INFO: 2022/07/26 23:25:23.850653 START TIME: 2022-07-26 23:10:27 GMT
INFO: 2022/07/26 23:25:23.850659 LABEL: 2022-07-26 23:10:27.545378 +0000 UTC m=+0.167723956
INFO: 2022/07/26 23:25:23.850665 START TIMELINE: 2
INFO: 2022/07/26 23:25:23.850669 
INFO: 2022/07/26 23:25:23.850676 ------------ LABLE FILE END ----------

How can we do PITR using timestamp if we don’t know the accurate timestamp of minimum recovery point ?






Thanks.Best,
Harinath

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