Re: Cancelling Requests Frontend/Backend Protocol TCP/IP

On 2/11/2009 5:15 PM, Raimon Fernandez wrote:

> For what I've read in the manuals, this operation is only valid before
> PostgreSQL has finished processing the SELECT statement ?
>
> If for example I send a SELECT * from myTable, it has 20000 rows, and
> postgre starts sending the rows, how I can cancel this operation ?

Assuming you're asking "is there any way to cancel a running query using
the postgresql tcp/ip protocol" then, as you've noted, you can cancel
the request until you start getting data.

After that, you can still cancel the query by establishing another
connection to the server and calling pg_cancel_backend( ) at the SQL
level. This does, unfortunately, involve the overhead of setting up and
tearing down a connection and the associated backend.

--
Craig Ringer