Subject: Re: dblink_error_message return value
To: Tom Lane <tgl@sss.pgh.pa.us>, realyota@gmail.com
Cc: pgsql-docs@lists.postgresql.org
References: <153371978486.1298.2091761143788088262@wrigleys.postgresql.org>
 <28231.1533743837@sss.pgh.pa.us>
From: Joe Conway <mail@joeconway.com>
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Message-ID: <1f9d1514-f087-1b11-9b45-aac91e57bdc2@joeconway.com>
Date: Tue, 25 Sep 2018 13:50:11 -0400
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From: Joe Conway <mail@joeconway.com>
To: Tom Lane <tgl@sss.pgh.pa.us>, realyota@gmail.com
Cc: pgsql-docs@lists.postgresql.org
Message-ID: <1f9d1514-f087-1b11-9b45-aac91e57bdc2@joeconway.com>
Subject: Re: dblink_error_message return value
References: <153371978486.1298.2091761143788088262@wrigleys.postgresql.org>
 <28231.1533743837@sss.pgh.pa.us>
In-Reply-To: <28231.1533743837@sss.pgh.pa.us>

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On 08/08/2018 11:57 AM, Tom Lane wrote:
> =3D?utf-8?q?PG_Doc_comments_form?=3D <noreply@postgresql.org> writes:
>> The following documentation comment has been logged on the website:
>> Documentation says:
>=20
>> Return Value
>> Returns last error message, or an empty string if there has been no er=
ror in
>> this connection.
>> Which is invalid.
>> Actually it returns 'OK' string if no error was raised.
>=20
> Good catch!  The code's quite clear about it, but the SGML docs need
> fixed.


As mentioned on the nearby thread, will fix. I suppose this ought to be
back-patched.


>> Secondly
>> dblink_is_busy must be first called to make dblink_error_message retur=
ns an
>> error message. (Tested on 9.6.9)
>=20
> Meh.  I see what you're getting at here, I think, but that seems like a=

> completely wrong/misleading statement of the issue.  Joe, can you think=
 of
> better phraseology?

Maybe a note, something like this?
------------
When asynchronous queries are initiated by dblink_send_query(), the
error message associated with the connection might not get updated until
the server's response message is consumed. This typically means that
dblink_is_busy() or dblink_get_result() should be called prior to
dblink_error_message(), so that any error generated by the asynchronous
query() will be visible.
------------

Joe

--=20
Crunchy Data - http://crunchydata.com
PostgreSQL Support for Secure Enterprises
Consulting, Training, & Open Source Development


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