Re: psql casts aspersions on server reliability

On 9/28/16 10:22 AM, Robert Haas wrote:
> On Wed, Sep 28, 2016 at 9:14 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
>>> psql tends to do things like this:
>>> rhaas=# select * from pg_stat_activity;
>>> FATAL: terminating connection due to administrator command
>>> server closed the connection unexpectedly
>>> This probably means the server terminated abnormally
>>> before or while processing the request.
>>
>>> Basically everything psql has to say about this is a lie:
>>
>> I cannot get terribly excited about this. What you seem to be proposing
>> is that psql try to intuit the reason for connection closure from the
>> last error message it got, but that seems likely to lead to worse lies
>> than printing a boilerplate message.
>>
>> I could go along with just dropping the last sentence ("This probably...")
>> if the last error we got was FATAL level. I don't find "unexpectedly"
>> to be problematic here: from the point of view of psql, and probably
>> of its user, the shutdown *was* unexpected.
>
> I don't care very much whether we try to intuit the reason for
> connection closure or not; it could be done, but I don't feel that it
> has to be done. My bigger point is that currently psql speculates
> that the reason for *every* connection closure is abnormal server
> termination, which is actually a very rare event.
>
> It may have been common when that message was added.
> 1a17447be1186fdd36391c58a2a0209f613d89c4 changed the wording this
> message in 2001, and the original message seems to date to
> 011ee13131f6fa2f6dbafd3827b70d051cb28f64 in 1996. And my guess is at
> that time the server probably did just roll over and die with some
> regularity. But today it usually doesn't. It's neither helpful nor
> good PR for libpq to guess that the most likely cause of a server
> disconnection is server unreliability.
>
> I have seen actual instances of customers getting upset by this
> message even though the server had been shut down quite cleanly. The
> message got into a logfile and induced minor panic. Fortunately, I
> have not seen this happen lately.

+1 for making this error message less frightening. I have also had to
explain it away on occasion.

--
-David
david(at)pgmasters(dot)net