RE: Timeout parameters

Hello Ryohei-san,

I understand the main aim of your suggestion that a client application has
to do a lot of work except making quires to the database. I agree with you
that "client-side timeout" has to be integrated into the PostgreSQL server
and libpq.
I'm with Fabien that "client-side timeout" seems unsafe. Also I agree with
Fabien that quire can take much time to be processed by the PosgtreSQL
server and it is a normal behavior. There is possible that performance of
the PostgreSQL server machine can be low temporary or continuously,
especially during upgrading procedure.
I think it is important to add some more information into the description
of this parameter which informs end-users that this parameter has to be
used very carefully because it can impact as on the client application as
on the server.

> You mentioned about when a SQL query is heavy, but I want to talk about
when OS hang.
> If OS hang occurs, the cost of cancel request processing is so high.

Such a situation looks to be covered by TCP_USER_TIMEOUT and keep_alive
mechanisms. May be it is better to warn in documentation or prohibit in
the source code to set "client-side timeout" less than TCP_USER_TIMEOUT to
avoid handling "possible" logical problems ahead to the network problems.
Keep in mind that "client-side timeout" can abort a connection which
uses UNIX-domain sockets too.

What do you think about it?

Best regards,
Mikalai Keida