Обсуждение: libpq: How to cancel a COPY ... TO statement?

Hi,

after sending a COPY ... TO statement with PQsendQuery(), how can I cancel it properly?

I tried using PQcancel(), but it seems to have no effect. Calling PQgetCopyData() or PQgetResult() afterwards does not
gointo a failure state. And I don't want to call PQgetCopyData() until it returns -1, as this might be a lot of data
beingread from the server that I don't need. 

BR, Daniel

Daniel Frey <d.frey@gmx.de> writes:
> after sending a COPY ... TO statement with PQsendQuery(), how can I cancel it properly?

> I tried using PQcancel(),

That's the correct way.

> but it seems to have no effect. Calling PQgetCopyData() or PQgetResult() afterwards does not go into a failure state.
AndI don't want to call PQgetCopyData() until it returns -1, as this might be a lot of data being read from the server
thatI don't need. 

You can't expect instantaneous response to a cancel.  For one thing, the
server might have already stuffed a good deal of data down the pipe.
You should keep pulling (and discarding) data until you get the end
or error response.

            regards, tom lane