Leslie,
It basically builds a bitmap, 1 bit for every record in the table, then using the indexes,
it can turn ranges of bits on and off, by ANDing and ORing the bitmaps for each clause it
determines what the recordset that need to be physically retrieved.
df - (Microsoft FoxPro MVP) http://www.geocities.com/ResearchTriangle/9834/
Quote:
>Can you tell what Rushmore optimization does in details? (besides of
>North By Northwest)
Rushmore