On Wed, Sep 28, 2016 at 9:14 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Robert Haas <robertmhaas@gmail.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.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company