Re: Add WAL recovery messages with log_wal_traffic GUC (was: add recovery, backup, archive, streaming etc. activity messages to server logs along with ps display)

On Fri, Apr 29, 2022 at 5:11 AM Bharath Rupireddy
<bharath(dot)rupireddyforpostgres(at)gmail(dot)com> wrote:
> Here's the rebased v9 patch.

This seems like it has enormous overlap with the existing
functionality that we have from log_startup_progress_interval.

I think that facility is also better-designed than this one. It prints
out a message based on elapsed time, whereas this patch prints out a
message based progress through the WAL. That means that if WAL replay
isn't actually advancing for some reason, you just won't get any log
messages and you don't know whether it's advancing slowly or not at
all or the server is just hung. With that facility you can distinguish
those cases.

Also, if for some reason we do think that amount of WAL replayed is
the right metric, rather than time, why would we only allow high=1
segment and low=128 segments, rather than say any number of MB or GB
that the user would like to configure?

I suggest that if log_startup_progress_interval doesn't meet your
needs here, we should try to understand why not and maybe enhance it,
instead of adding a separate facility.

--
Robert Haas
EDB: http://www.enterprisedb.com