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: 2021-01-20T17:47:47Z
Lists: pgsql-hackers 
Robert Haas <robertmhaas@gmail.com> writes:
> On Wed, Jan 20, 2021 at 12:19 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> 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.

> I'm not saying that which socket I used is totally irrelevant although
> in most cases it's going to be a lot of detail. I'm just saying that,
> at least for me, when you say you can't connect to a socket, I at
> least think about the return value of connect(2), which was clearly 0
> here.

Fair.  One possibility, which'd take a few more cycles in libpq but
likely not anything significant, is to replace "could not connect to ..."
with "while connecting to ..." once we're past the connect() per se.

> Maybe it would be better if it said:

> connection to database at socket "/tmp/.s.PGSQL.5432" failed: FATAL:
> database "rhaas" does not exist

I'd be inclined to spell it "connection to server at ... failed",
but that sort of wording is surely also possible.

			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.