Re: confusion between max_standby_archive_delay, max_standby_archive_delay and max_standby_archive_delay

On Sun, 2023-03-12 at 01:53 +0530, Atul Kumar wrote:
> Could someone help me in telling the difference between these three parameters 
> 1. max_standby_archive_delay
> 2. max_standby_streaming_delay
> 3. recovery_min_apply_delay
>
> My basic motive is to make the standby database server to be delayed to apply the
> changes on itself,  if any data has been accidentally deleted/updated/ truncated
> from the primary server.
>
> Which parameter do I need to configure to serve this purpose ? And 
> When will the remaining two parameters be used ?
>
> It would be great if anyone can explain them with a brief example.

The parameter that does what you describe you want is "recovery_min_apply_delay".

The other parameters only deal with delaying replication in the face of a
replication conflict.

Note that changes are immediately shipped to the standby, what is delayed with
"recovery_min_apply_delay" is only the replay of the WAL information.

So you can recover from a logical problem like DROP TABLE by stopping the
standby, setting "recovery_target_time" to a time before the problem happened
and then restarting the standby. Then recovery will stop before the problem
is replayed.

Yours,
Laurenz Albe