Re: A streaming replica catching up

On Thu, 2021-04-22 at 10:16 +0700, Victor Sudakov wrote:
> After a streaming standby has been down for a time, I know of two
> options for it to catch up with the master:
>
> 1. The replica can fetch all the necessary WAL records via the
> replication protocol from the master (unless max_slot_wal_keep_size is
> not the default -1, all the required WAL archives should be available from
> the master).
>
> 2. The replica can be provided with a restore_command and will fetch
> all WAL files from the WAL archive before starting streaming WAL from
> the master.
>
> Which is the preferred way?
>
> Of course if max_slot_wal_keep_size is limited, the second options seems
> the only safe one.
>
> OTOH, if the master does not write to a WAL archive, only the first
> option is left to us.

Both methods are equally feasible. Which one you choose depends on
your situation, just as you describe in the last two sentences.

Yours,
Laurenz Albe
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