5 Tricky Questions on VSAM alternate Index

The below are the list of questions on alternate index in VSAM.

Q1). What is alternate index?

A1). VSAM -Alternate index only allowed on KSDS and ESDS, but not on RRDS

Q2). Why do you need alternate index?

A2). Alternate index should be declared for alternate key,and a path. So alternate key is different from alternate index. The path behaves like we are accessing a record from KSDS or ESDS cluster.

Q3). What is path?

A3) Path is for Alternate Index. Base is main cluster.

Q4) When do you update alternate index?

A4). When you update a record by path, the alternate index is automatically updated

Q5) How to define alternate index in CICS applications?

A6). For CICS application program to access a file that has been directly defined as an alternate index rather than a path. This results in index data being returned to the application program rather than file data. This operation is not supported for files opened in record-level sharing (RLS) mode.

Related: More tips on VSAM alternate index


Author: Srini

Experienced software developer. Skills in Development, Coding, Testing and Debugging. Good Data analytic skills (Data Warehousing and BI). Also skills in Mainframe.