Fields in the SHISAM secondary index pointer

SHISAM secondary index databases are not required to register to DBRC. A SHISAM secondary index database supports only unique keys because a SHISAM database supports only KSDSs, not ESDSs.

A SHISAM secondary index database supports the subsequence field, the duplicate data field, the user data field, and the /CK operand. The subsequence field and the /CK operand can be used to make the secondary index key unique.

A SHISAM secondary index database contains fixed-length segments, provides data partitioning using the DEDB Partition Selection exit routine, and supports the Segment edit/compression exit routine.

Figure 1. Example of a SHISAM secondary index pointer
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Logical record
A secondary index pointer segment is stored in a logical record.
Pointer segment
A secondary index pointer segment contains prefix and data fields. Because SHISAM secondary index segments do not have a prefix field, a secondary index pointer segment contains only data fields.
Data fields
Search field
Variable-length bytes, including up to 5 fields from the source. The search field is the key of the secondary index.
Subsequence field (optional)
Variable-length bytes, including up to 5 fields from the source or IMS-generated values. The subsequence field makes the secondary index key unique, and can be used to order segments in a secondary index database. Subsequence length is used to determine the concatenated key length.
Duplicate data field (optional)
Variable-length bytes, including up to 5 fields from the source. The field is used only when processing the secondary index as a database.
Symbolic pointer concatenated key field
Variable-length bytes. The field is the concatenated key to the target.
User data field (optional)
Variable-length bytes, including any user data fields. The field is used only when processing the secondary index as a database.