Re: duplicate connection failure messages

On Wed, Oct 13, 2010 at 21:21, Peter Eisentraut <peter_e(at)gmx(dot)net> wrote:
> This surprised me:
>
> psql -p 55555 -h localhost
> psql: could not connect to server: Connection refused
>        Is the server running on host "localhost" and accepting
>        TCP/IP connections on port 55555?
> could not connect to server: Connection refused
>        Is the server running on host "localhost" and accepting
>        TCP/IP connections on port 55555?
>
> It shows the same error message twice.  I can reproduce this back to PG
> 8.2.
>
> It appears to have something to do with localhost resolving to an IPv4
> and an IPv6 address, since it doesn't happen with other host names that
> only resolve to one address.  However, fe-connect.c claims:
>
>    /*
>     * Try to initiate a connection to one of the addresses
>     * returned by pg_getaddrinfo_all().  conn->addr_cur is the
>     * next one to try. We fail when we run out of addresses
>     * (reporting the error returned for the *last* alternative,
>     * which may not be what users expect :-().
>     */

That comment is out of date. I implemented the "keep all error
messages and append them to each other" feature to make sure it didn't
throw away the interesting error message and replaced it with a
generic one later, must've missed that comment - at least it should be
changed. And I agree it's not very friendly in this specific case - I
wonder if we should log it as "localhost (127.0.0.1) and "localhost
(::1)" (and similar for any other case that returns more than one
address).

--
 Magnus Hagander
 Me: http://www.hagander.net/
 Work: http://www.redpill-linpro.com/