Re: Log connection establishment timings

Hi,

On 2025-02-27 11:08:04 -0500, Melanie Plageman wrote:
> I was just talking to Andres off-list and he mentioned that the volume
> of log_connections messages added in recent releases can really be a
> problem for users.

For some added color: I've seen plenty systems where almost all the log volume
is log_connection messages, which they *have* to enable for various regulatory
reasons. It'd still be a lot if we just emitted one message for each
connection, but logging three (and possibly four with $thread), for each
connection makes it substantially worse.

> He said ideally we would emit one message which consolidated these (and make
> sure we did so for failed connections too detailing the successfully
> completed stages).

A combined message would also not *quite* replace all use-cases, e.g. if you
want to debug arriving connections or auth problems you do want the additional
messages. But yea, for normal operation, I do think most folks want just one
message.

> However, since that is a bigger project (with more refactoring, etc),
> he suggested that we change log_connections to a GUC_LIST
> (ConfigureNamesString) with options like "none", "received,
> "authenticated", "authorized", "all".

Yep.

> Then we could add one like "established" for the final message and
> timings my patch set adds. I think the overhead of an additional log
> message being emitted probably outweighs the overhead of taking those
> additional timings.

To bikeshed a bit: "established" could be the TCP connection establishment
just as well. I'd go for "completed" or "timings".

> String GUCs are a lot more work than enum GUCs, so I was thinking if
> there is a way to do it as an enum.
>
> I think we want the user to be able to specify a list of all the log
> messages they want included, not just have each one include the
> previous ones. So, then it probably has to be a list right? There is
> no good design that would fit as an enum.

I don't see a way to comfortably shove this into an enum either.

Greetings,

Andres Freund