The alternate index is used to access records other than base key.
The dataset over which alternate index defined is called base cluster.
- Can be defined for both KSDS and ESDS
- reduce data redundancy
- Can have duplicates
- Easy to define using IDCAMS
- allow datasets to be accessed by both sequentially and randomly
- Performance degradation
- Complex update logic
- The merits of VSAM alternate index
- The VSAM real story of merits and demerits
- VSAM access modes for files awesome details