Re: psql casts aspersions on server reliability

On 28/09/16 17:13, David Steele wrote:
> 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.
>

+1 I've seen this being misleading way too often.

--
Petr Jelinek http://www.2ndQuadrant.com/
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