Short Version:
I've read the idocs and Notes and Googled a fair amount, honest. :-)
What's the most efficient way of determining the number of rows in a
cursor's result set if you really *DO* need that? (Or, rather, if your
client specifically asked for features that require that.)
Long Version:
I'm not finding any way in the docs of asking a cursor how many rows total
are in the result set, even if I do "move 1000000 in foo", knowing a
priori that 1000000 is far more than could be returned.
Oracle docs seem to have a SQL.%ROWCOUNT which gives the answer, provided
one has moved beyond the last row... If I'm reading the Oracle docs
right...
Anyway. I could find nothing similar in PostgreSQL, even though it seems
reasonable, even for a Portal, provided one is willing to do the "move X"
for X sufficiently high -- And, in fact, psql outputs the precise number
of rows when I do that in the psql monitor, so at some level PostgreSQL
"knows" the answer I want, but I can't get that "MOVE XX" output into PHP,
as far as I can tell. (Can I?)
I suppose I could, in theory, use PHP to fire up psql, but that's not
exactly going to be efficient, much less pleasant. :-)
Using PHP, if it matters. I guess it does since maybe other APIs have
some way to access that number I want -- psql sure seems to print it out
when one goes over the edge.
Given that the count(*) queries take just as long as the actual
data-retrieval queries, and that some of my queries take too long as it is
(like, a minute for a 4-term full text search)...
I've written and am about to benchmark a binary search using a bunch of
"move X" "fetch 1" "move backward 1" "move backward X" and then using Ye
Olde Low/High guessing game algorithm to find the number of rows, but I'm
hoping for something better from the optimization experts.
Sorry this got a bit long, but I wanted to be clear about where I've been
and gone, rather than leave you guessing. :-)
Hope I didn't miss some obvious solution/documentation "out there"...