Re: pg_isready bug

From: Michael Paquier <michael(at)paquier(dot)xyz>
To: Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr>
Cc: "Hunosau, Aliaksei" <ahunosau(at)scnsoft(dot)com>, "pgsql-bugs(at)postgresql(dot)org" <pgsql-bugs(at)postgresql(dot)org>
Subject: Re: pg_isready bug
Date: 2020-04-14 00:33:37
Message-ID: 20200414003337.GB1492@paquier.xyz
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On Mon, Apr 13, 2020 at 04:17:21PM +0200, Fabien COELHO wrote:
> Basically a connection is merely attempted, but it does not report success
> of said connection. The sentence of "pg_isready --help" is somehow
> ambiguous:
>
> "pg_isready issues a connection check to a PostgreSQL database.", but no one
> specified whaa a "connection check" is. I can understand that you would
> expect to be an actual connection:-)
>
> ISTM that the doc should be clarified about what is a "connection check",
> and that it is not working a connection.

Yeah, that matches my impression when reading this thread. Perhaps
the docs had better emphasize that --timeout is a simple mapping for
the connection parameter connect_timeout in this case? My point is
that the logic tells us that the timeout is in effect when a
connection has been started, but not completed yet. And the docs of
pg_isready tell us that:
"The maximum number of seconds to wait when attempting connection
before returning that the server is not responding."

So this does not really insist on the point that a timeout has no
effect on a connection immediately failing because of an incorrect
parameter set.
--
Michael

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