Integrated Data Dictionary Mapping Entities › Data Dictionary Entities Used by the Mapping Compilers › Record Occurrences

Record Occurrences

What is a Record Occurrence?

A record occurrence is the basic addressable unit of data in CA IDMS/DB. A record consists of a fixed or variable number of characters subdivided into units called elements. Records that are used by maps must be defined in the dictionary prior to map compilation.

Establishing a Record Occurrence

Record occurrences can be established in the data dictionary in one of the following ways:

• The ADD RECORD statement submitted to the DDDL compiler establishes a record entity occurrence in the data dictionary.

  Note: For more information about the ADD RECORD statement and other DDDL statements, see the CA IDMS IDD DDDL Reference Guide.

• The RECORD DESCRIPTION SECTION of the schema DDL submitted to the schema compiler establishes record entity occurrences in the data dictionary.

  Note: For more information about the DDL schema compiler, see the CA IDMS Utilities Guide.

Considerations

The following considerations apply to the modification or deletion of records:

• If a record participates in a CA IDMS/DB schema, the record cannot be deleted from the dictionary. Additionally, no structural modifications can be made to the record; however, commentary and documentational entries can be added or modified.
• A record synonym that participates in a CA IDMS/DB schema, subschema, or CA IDMS map cannot be removed or excluded from the dictionary.
• A view id (established by a DDDL PROGRAM statement) that is active in a CA IDMS/DB subschema cannot be removed from the dictionary.
• A record that participates in a map can be modified, with the following exceptions:
  • A record element that participates in a map cannot be removed from the record or replaced. This restriction applies also to group elements that contain subordinate elements that participate in maps. REPLACE RECORD ELEMENTS implicitly performs a remove and an insert operation.

    Several DDDL commands cause the removal or replacement of record elements. If the record elements or subordinate elements to be removed or replaced participate in maps, the operation is not performed. If the record elements or subordinate elements do not participate in maps, the operation is performed as usual. The following commands perform a remove operation:

    • REMOVE RECORD ELEMENT
    • REPLACE RECORD ELEMENT
    • REMOVE ALL
    • COBOL substatement

    The following commands perform a replace operation:

    • REBUILD RECORD ELEMENTS followed by RECORD ELEMENT substatements
    • REPLACE RECORD ELEMENT
  • The occurrence count of the OCCURS clause cannot be decreased if the decrease causes a map field to be made obsolete. For example, if the twelfth occurrence of a record element is used by a map, and an attempt is made to modify the record and decrease the occurrence count to eleven, an error occurs and the modification is not performed. This rule applies to group record elements as well as to elementary record elements.
• Certain modifications to map-owned occurrences require that the map be recompiled if the map is to reflect the changes in the occurrence. Other modifications require that the map, as well as the programs using the map, be recompiled.

  Note: For more information, see Critical Changes.