On Tue, 2006-08-08 at 12:49, Patrice Beliveau wrote: > Hi, > > I have a query that use a function and some column test to select row. > It's in the form of: > > SELECT * FROM TABLE > WHERE TABLE.COLUMN1=something > AND TABLE.COLUMN2=somethingelse > AND function(TABLE.COLUMN3,TABLE.COLUMN4) > 0; > > The result of the function does NOT depend only from the table, but also > from some other tables. > > Since it's long to process, I've add some output to see what's going on. > I find out that the function process every row even if the row should be > rejected as per the first or the second condition. Then , my question > is: Is there a way to formulate a query that wont do all the check if it > does not need to do it ? Meaning that, if condition1 is false then it > wont check condition2 and that way the function will only be called when > it's really necessary. What version of postgresql are you running? It might be better in later versions. The standard fix for such things is to use a subquery... select * from ( select * from table where col1='something' and col2='somethingelse' ) as a where function(a.col3,a.col4) > 0;
