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Re: Deterministic functions not recognized by optimizer - will they ever?

From: Serge Rielau <srielau_at_ca.ibm.com>
Date: Tue, 16 Apr 2002 11:51:44 -0400
Message-ID: <3CBC4890.A742EB10@ca.ibm.com> 





Hi,



DB2 UDB remembers the last input to a determinstic function. If it didn't change
it will skip the call and recycle the last output.
For constant expressions based on parameter markers  DB2 also has the concept of
a "once only".


Finally there is such a thing as constant folding which evaluates various
builtin functions at compiletime


(such as: (5 + 6)).



Cheers


Serge

--
Serge Rielau
DB2 UDB SQL Compiler Development
IBM Software Lab, Canada


Received on Tue Apr 16 2002 - 10:51:44 CDT












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