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DL/I and CA IDMS/DB › DL/I and CA IDMS/DB Correspondences

DL/I and CA IDMS/DB Correspondences

CA IDMS DLI Transparency allows a DL/I application program to access a CA IDMS/DB database. To support this access, you must define a CA IDMS/DB schema and subschema that correspond to the specific DBD and PSB definitions expected by the application. For example, for each DL/I segment, hierarchy, and logical relationship, you must make sure that there is a corresponding CA IDMS/DB record type and set structure.

Note: For more information about the rules for defining schemas and subschemas, see the CA IDMS Database Administration Guide.

The following table summarizes the required correspondences between DL/I and CA IDMS/DB.

DL/I structure

CA IDMS/DB equivalence

Segment

Record

Parent segment

Owner record

Child segment

Member record

Parent/child relationship

Set relationship where parent is the owner and the child is the member

Child segment with a sequence field

Member record of a sorted set

Sequence field for a dependent segment

Sort key

Unsequenced child segments with insert rules as follows:

  • HERE
  • FIRST
  • LAST

Member record of a set with an order option as follows:

  • PRIOR
  • FIRST
  • LAST

Child segments with nonunique sequence fields with an insert rule as follows:

  • FIRST
  • LAST

Member record of a sorted set with the following duplicates option:

  • FIRST
  • LAST

Child segments with nonunique sequence fields with an insert rule of HERE*

Member record of a set with a set order option of PRIOR

Logical relationship

  • Physical parent segment
  • Logical parent segment
  • Logical child segment

Many to many relationship

  • Owner record
  • Owner record
  • Junction record

Dependent segments in a physical access database

Members of a CA IDMS/DB set

Root segment in an ACCESS=HDAM database

CALC record

Root segment in an ACCESS=HISAM database

DIRECT record in a SYSTEM-owned indexed set; ascending or descending sort order on the record's symbolic key (equivalent to the sequence field of the HISAM root segment)

Root segment in an ACCESS=INDEX database (pointer segment)

Member record in a SYSTEM-owned indexed set; ascending sort order on the record's symbolic key (equivalent to the sequence field of the index pointer segment); also, VIA member in a set owned by the target record

Pointer segment (root segment in the corresponding ACCESS=INDEX database)

Member record in a SYSTEM-owned indexed set; ascending sort order on the record's symbolic key (equivalent to the sequence field of the index pointer segment); also, VIA member in a set owned by the target record

Target segment (root segment)

CALC record that owns the pointer record in the target-pointer set

Secondary index target segment

Owner record of a target-pointer set

Pointer segment (root segment of the corresponding ACCESS=INDEX database)

Record that is a member of an indexed set sorted in ascending order on the value of the sort key (i.e. the sequence field for the equivalent segment); record is also a VIA member of a set owned by the target record

ACCESS=HIDAM database:

  • Root segment (target segment)

Record equivalents for ACCESS-HIDAM database:

  • CALC record that owns a pointer record through the target-pointer set

Note: *Special considerations apply to insert rules (see Sequenced and Unsequenced Child Segments).