Horton

Re: strange error reporting

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
Cc: "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2021-01-20T17:19:29Z
Lists: pgsql-hackers 
Robert Haas <robertmhaas@gmail.com> writes:
> I just made the mistake of trying to run pgbench without first running
> createdb and got this:

> pgbench: error: connection to database "" failed: could not connect to
> socket "/tmp/.s.PGSQL.5432": FATAL:  database "rhaas" does not exist

> This looks pretty bogus because (1) I was not attempting to connect to
> a database whose name is the empty string and (2) saying that it
> couldn't connect to the socket is wrong, else it would not also be
> showing a server message.

I'm not sure about the empty DB name in the first part (presumably
that's from pgbench, so what was your pgbench command exactly?).
But the 'could not connect to socket' part is a consequence of my
recent fiddling with libpq's connection failure reporting, see
52a10224e.  We could discuss exactly how that ought to be spelled,
but the idea is to consistently identify the host that we were trying
to connect to.  If you have a multi-host connection string, it's
conceivable that "rhaas" exists on some of those hosts and not others,
so I do not think the info is irrelevant.

Just looking at this, I wonder if we ought to drop pgbench's
contribution to the message entirely; it seems like libpq's
message is now fairly freestanding.

			regards, tom lane

Commits

  1. pgbench: Remove dead code

  2. Report the true database name on connection errors

  3. Avoid redundantly prefixing PQerrorMessage for a connection failure.

  4. Improve new wording of libpq's connection failure messages.