Although the FETCH function was specifically designed for indexed access to data, in practice the half-keyed JOIN operation is more commonly used in Roxie queries. A major reason for this is the flexibility that is possible with JOIN.

The advantages of using keyed JOIN operations in any query is fully discussed in the Using ECL Keys (INDEX Files) article. These advantages really benefit Roxie queries tremendously. Because of the nature of Roxie, the best advantage from keyed JOINs comes from the use of half-keyed JOINs that utilize payload keys (eliminating the need for additional FETCH operations).