Re: SELECT COUNT(APPROXIMATELY *) FROM a WHERE b=c;

Here's an optimistic option.

CBO returns a computed cardinality on
explain plan, so you could (in principle) return that as an indication of the number of rows to be returned.

--
Jonathan Lewis
http://www.jlcomp.demon.co.uk

Next Seminars
        UK            June / July
        Australia      July / August
http://www.jlcomp.demon.co.uk/seminar.html

Connor McDonald wrote in message <3D063FF5.263D_at_yahoo.com>...


>Monty wrote:

>>

>> Hello, every now and then I go to a website, perform a search, and it

>> comes back and says "found APPROXIMATELY ? records".

>>

>> A case in point is "http://asktom.oracle.com" (click on

>> Search/Archives, type in something in the search box, and press go)

>> and I am probably not wrong in assuming there is an Oracle database

>> behind this web site.

>>

>> How can an SQL search be formulated to find approximately the number

>> of hits (which I'm assuming is just a quick preview of a very large

>> database with a query before actually doing the 'real' query) ?

>>

>> Monty

>

>I'm guessing either

>

>a) intermedia indexes only being refreshed every 'n' hours

>b) using a sample clause to speed the results

>