On Thursday 07 July 2005 20:43, Alvaro Herrera wrote: > On Thu, Jul 07, 2005 at 08:17:23AM -0700, John R Pierce wrote: > > Neil Conway wrote: > > >Denis Vlasenko wrote: > > > > > >>The same php script but done against Oracle does not have this > > >>behaviour. > > > > > > > > >Perhaps; presumably Oracle is essentially creating a cursor for you > > >behind the scenes. libpq does not attempt to do this automatically; if > > >you need a cursor, you can create one by hand. > > > > I do not understand how a cursor could be autocreated by a query like > > > > $result = pg_query($db, "SELECT * FROM big_table"); > > > > php will expect $result to contain the entire table (yuck!). > > Really? I thought what really happened is you had to get the results > one at a time using the pg_fetch family of functions. If that is true, > then it's possible to make the driver fake having the whole table by > using a cursor. (Even if PHP doesn't do it, it's possible for OCI to do > it behind the scenes.)
Even without cursor, result can be read incrementally. I mean, query result is transferred over network, right? We just can stop read()'ing before we reached the end of result set, and continue at pg_fetch as needed. This way server does not need to do any of cursor creation/destruction work. Not a big win, but combined with reduced memory usage at client side, it is a win-win situation. -- vda ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend
