The Behaviour about a where statement with static content have change from Firebird 1.5/2.1 to 2.5 and have a massiv impact in our case. The static statement like (select sValue From spr_test('SIMSIM')) is evaluated 1 time in firebird 1.5 and 2.1, the number of row in the from-clause with firebird 2.5 (about 45'000 in our case).

You can test it with the following script:

-------------------------------------------------------------------------------
-- Init
-------------------------------------------------------------------------------
Create Table tt_table(Field1 varchar(100));
go

Create Or Alter PROCEDURE SPR_TEST (pName Varchar(2000)) RETURNS (sValue Varchar(255)) AS
BEGIN
  Insert Into tt_table(field1) values(:pName);
  sValue=:pName;
  suspend;
End
go

-------------------------------------------------------------------------------
-- Call procedure
-------------------------------------------------------------------------------
Select count(*)
from rdb$types
where rdb$field_name like (select sValue From spr_test('SIMSIM'))
go

-------------------------------------------------------------------------------
-- Result is 1 with Firebird 1.5 and 2.1, 225 with Firebird 2.5
-------------------------------------------------------------------------------
Select count(*) From tt_table
go

-------------------------------------------------------------------------------
-- Clean
-------------------------------------------------------------------------------
Drop Procedure spr_test
go
Drop Table tt_table
go

Thank you for your big work with Firebird, its a very good thing!