Thanks, I know how the composite index work. I had some other questions ....

Que1. Auth_ID is a Primary key on this table, then why do you have to include that to
a composite index.

If this is not used then adding it to a composite index make it worst ?

Que2. Why is it recommending to do LOGGING on only one composite index IX_AUTH_WORK
and not all ?
Que3. AUTH_WORK_ID and AUTH_RES_ID are foreign keys, should these be 1st in the
composite index to make sure that they will be used always !
Que4. Will separate indexes make it better than composite indexes.