But the function foo() would produce different values for the two queries, so the result will be different. A simple example is foo() computes the sum of all the integer fields of the input record.
On 1/26/06, Peter Eisentraut <[EMAIL PROTECTED]> wrote: > andrew wrote: > > Sorry for the confusion. This is what i meant. Thanks, Michael. > > > > select * > > from (select * from A, B where A.a = B.b) as s > > where foo(s) < 2; > > > > On 1/25/06, Peter Eisentraut <[EMAIL PROTECTED]> wrote: > > > andrew wrote: > > > > I want to use a UDF to filter tuples t that are generated after a > > > > join. More specifially, I have a UDF foo(record), which computes > > > > a value for a given tuple. I can do the filtering before the > > > > join. e.g.: > > > > > > > > select * from A, B where foo(A)<2 and A.a=B.b; > > Note that these two queries will produce the same internal execution > plan, so if you wanted to make some difference you will not. > > -- > Peter Eisentraut > http://developer.postgresql.org/~petere/ > -- andrew ---------------------------(end of broadcast)--------------------------- TIP 4: Have you searched our list archives? http://archives.postgresql.org
