>>Hello fellow weekend-workers <g>,
>>
>>I am changing a candidate key on many of my tables from a single field to a composite expression (e.g. TBL_ID_FLD + BINTOC(TBL_INT_FLD)). My question is, do I also need to create a regular index on the TBL_ID_FLD in order for Rushmore to find records faster? That is, will Rushmore use the composite index key? (and if so, I can save on not having to create an extra index tag).
>>
>>Thank you in advance for any questions.
>
>Hi Dmitry,
>
>The potential problem is the following. If the key is made up of data provided by the user, you will need to filter the index on not deleted(). Otherwise, if the user deletes the record and creates a record with the same key again, he will get an error message to the effect that the record already exists.
>
>A filtered index can't be used for Rushmore optimization.
>
>On the other hand, it is a little doubtul that you will do a query precisely on the expression you specified - unless you use the exact expression explicitly.

In VFP 9 they can be used:

CLEAR
SET DELETED ON
CREATE CURSOR Test (TBL_ID_FLD C(20),TBL_INT_FLD int)
INDEX ON TBL_ID_FLD + BINTOC(TBL_INT_FLD) FOR NOT DELETED() TAG Test
SYS(3054,12)
SELECT * FROM Test;
WHERE TBL_ID_FLD + BINTOC(TBL_INT_FLD) LIKE 'asdasdasda%' INTO CURSOR crsTest    && Full
?
SELECT * FROM Test;
WHERE TBL_ID_FLD + BINTOC(TBL_INT_FLD) = 'asdasdasda' INTO CURSOR crsTest        && Full
SYS(3054,12)