>> > I'm communicating with psql via a pipe stream. This works
>pretty well,
>> > but one problem I have is trying to cancel an operation.
>If I send a
>> > sigint, psql dies. In looking at the source I gather this
>is because
>> > it assumes I'm in non-interactive mode (pset.notty is true). I was
>> > wondering if there was some way to work around this short of
>> > recompiling the source. I need to do the same thing on Windows.
>> >
>> > Thanks for any suggestions,
>>
>> On Unix you could run 'psql' through a pty rather than a pipe. No
>> idea what the Windows equivalent would be.
>
>We don't have signals on win32 like we have on Unix so we
>simulate them.
>Not sure it is possible to signal psql like you want on Win32.

There is no way so signal *psql*, as in the client side process. The
signal emulation only runs in the server.

You can do the same thing in the server using pg_ctl kill, but that
won't work on client processes.

//Magnus

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On Feb 21, 2005, at 3:00 PM, Magnus Hagander wrote:

> There is no way so signal *psql*, as in the client side process. The
> signal emulation only runs in the server.
>
> You can do the same thing in the server using pg_ctl kill, but that
> won't work on client processes.

Thanks to everyone for the feedback and suggestions. Since I need this
to work on win32, I guess I'll just abort the stream and reconnect. The
main issue with this is trying to restore any state associated with the
connection (e.g. search_path).


John DeSoi, Ph.D.
http://pgedit.com/
Power Tools for PostgreSQL


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Hi Magnus,

On Feb 21, 2005, at 3:00 PM, Magnus Hagander wrote:

> There is no way so signal *psql*, as in the client side process. The
> signal emulation only runs in the server.
>

But is there some equivalent of pressing ctrl-C to make psql stop what
it is doing? For example, through the pipe stream I may execute a \i
command and the user wants to stop before the file is processed. What
mechanism is used to do this on win32? I thought it could be
accomplished on Unix with kill -2, hence my original question. But
maybe I'm looking in the wrong place.

Thanks,


John DeSoi, Ph.D.
http://pgedit.com/
Power Tools for PostgreSQL


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John DeSoi wrote:
> Hi Magnus,
>
> On Feb 21, 2005, at 3:00 PM, Magnus Hagander wrote:
>
> > There is no way so signal *psql*, as in the client side process. The
> > signal emulation only runs in the server.
> >
>
> But is there some equivalent of pressing ctrl-C to make psql stop what
> it is doing? For example, through the pipe stream I may execute a \i
> command and the user wants to stop before the file is processed. What
> mechanism is used to do this on win32? I thought it could be
> accomplished on Unix with kill -2, hence my original question. But
> maybe I'm looking in the wrong place.

Win32 doesn't have the granularity to do special signal numbers like we
do on Unix, so we have to map control-C to call a special libpq function
that communicates with the postmaster/backend to cancel the query. No
way an outside process can do that.

Your only solution would be to hack psql to accept a signal somehow to
call that libpq function, and hack your client to send that signal to
psql somehow.

--
Bruce Momjian | http://candle.pha.pa.us
pgman@candle.pha.pa.us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073

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