Re: Hints difference between AND_EQUAL, INDEX_JOIN and INDEX_COMBINE

On Fri, 16 Dec 2005 11:12:21 -0800, Jason wrote:

> Does anyone know the real difference between these hints? I've read
> the documentation in the "Oracle 9i Database Performance Tuning Guide
> and Reference" and the "Oracle 9i SQL Reference". Both seem to say the
> same thing just in different fashions, essentially, combining indexes
> for a better access path. INDEX_COMBINE appears to be only for
> bitmapped indexes so I assume the other 2 hints are for normal indexes
> (although the documentation doesn't state this explicitly).
>

Index join joins two tables by merging their indexes. And-equal merges two indexes on the same table to resolve a query. It is the same process of index merge, but to different end. And-equal resolves both conditions separately and then extracts common rowids. Index join resolves both queries on respective tables separately and then extracts common keys.

I've never had any chance to use INDEX_COMBINE, so I don't know much about it.

-- 
http://www.mgogala.com