If you use a composite index on COLUMN_A, COLUMN_B it can be used on
where clauses specifying both columns or where clauses specifying only
COLUMN_A; however it cannot be used for where clauses that specify only
COLUMN_B.
Two single column indexes cover all three sets of where clauses, but the
I believe composite is quicker when both columns are specified.
jean-christophe.nedelec_at_wanadoo.fr wrote:
> i wonder what is the best for retrieval on 2 table with 2 columns
> - 2 index on each columns
> - a composite index on the 2 column ?
Received on Mon Mar 22 1999 - 21:04:18 CST
