Amir Michail <[EMAIL PROTECTED]> writes: > Hi, > > Given some condition, how do you efficiently check whether there is at > least one row that satisfies that condition? > > count(*) is slow.
To check whether there are any rows in the table T where X < 4, you could do something like this: VALUES 1 INTERSECT SELECT 1 FROM T WHERE X < 4 (returns one row if there's a match, zero rows otherwise) This should stop immediately when it finds a matching row. If there are no matching rows, the entire table will be scanned unless you have an index on the column X. -- Knut Anders
