Database Structure Question - Keys

Supposed I have a database table of millions of transaction records. In nearly every case, I need to access the records by customer ID and date. So nearly all queries will look something like

SELECT ........ WHERE CUSTOMER_ID=x AND TRANSACTION_DATE=y ......

The number of customers is realatively small compared to the number of database records (+/-50).

So a

SELECT .... WHERE CUSTOMER_ID=X could return millions of records.

SELECT .... WHERE TRANSACTION_DATE=y

could return a few million records.

SELECT ........ WHERE CUSTOMER_ID=x AND TRANSACTION_DATE=y ......

would return tens to hundreds of thousand records.

QUESTION: In such a situation on Oracle, is one better off defining two keys on CUSTOMER_ID and TRANACTION_DATE or is it better to have one compound key consisting of both columns? Received on Mon Jul 16 2007 - 10:54:42 CDT