Re: about cursors

On Sat, Jun 16, 2007 at 09:58:27AM -0700, Ottavio Campana wrote:
> At this point I'm not able to understand any more if cursor are useful
> to reduce computational needs compared to running the same query each
> time with limit and offset.

A cursor is generally much cheaper because you only execute the query
once. You only have parse/plan/initialise/execute the query once. For
expensive queries this can be a huge saving. If you have a table with
10 million records, a cursor will only go through the table once.

> One last question: what happens to unclosed cursors? I mean, suppose an
> application opens a cursor and crashes. What happens to that cursor? Is
> there a way to close idle cursors?

Cursors are attached to the transactio and session, if either ends, the
cursor dies with it...

Have a nice day,
--
Martijn van Oosterhout   <kleptog@svana.org>   http://svana.org/kleptog/
> From each according to his ability. To each according to his ability to litigate.