Re: Mop-up around psql's \connect behavior

Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com> writes:
> At Thu, 22 Oct 2020 15:23:04 -0400, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote in
>> ... The only real objection I can see is that it could
>> hold a server connection open when the user thinks there is none;
>> but that could only happen in a non-interactive script, and it does
>> not seem like a big problem in that case. We could alternatively
>> not stash the "dead" connection after a non-interactive \connect
>> failure, but I doubt that's better.

> Agreed. Thanks!

After further thought I decided we *must* do it as per my "alternative"
idea. Consider a script containing
\c db1 user1 live_server
\c db2 user2 dead_server
\c db3
The script would be expecting to connect to db3 at dead_server, but
if we re-use parameters from the first connection then it might
successfully connect to db3 at live_server. This'd defeat the goal
of not letting a script accidentally execute commands against the
wrong database.

So we have to not save the connection after a failed script \connect.
However, it seems OK to save after a connection loss whether we're
in a script or not; that is,

\c db1 user1 server1
...
(connection dies here)
... --- these commands will fail
\c db2

The script will be expecting the second \c to re-use parameters
from the first one, and that will still work as expected.

I went ahead and pushed it after adjusting that.

regards, tom lane