> 23 июля 2019 г., в 21:05, Jehan-Guillaume de Rorthais <j...@dalibo.com>
> написал(а):
>
> Fetching the timeline from a standby could be useful in various situation.
> Either for backup tools [1] or failover tools during some kind of election
> process.
That backup tool is reading timeline from pg_control_checkpoint(). And formats
WAL file name itself when necessary.
> Please, find in attachment a first trivial patch to support pg_walfile_name()
> and pg_walfile_name_offset() on a standby.
You just cannot format WAL file name for LSN when timeline changed. Because
there are at least three WALs for that point: previous, new and partial.
However, reading TLI from checkpoint seems safe for backup purposes.
The only reason for WAL-G to read that timeline is to mark backup invalid: if
it's name is base_00000001XXXXXXXXYY00000YY and timeline change happens, it
should be named base_00000002XXXXXXXXYY00000YY (consistency point is not on TLI
2), but WAL-G cannot rename backup during backup-push.
Hope this information is useful. Thanks!
Best regards, Andrey Borodin.
[0] https://github.com/wal-g/wal-g/blob/master/internal/timeline.go#L39
