Changing Relationship Criteria

From the Criteria : Subset Selection panel, FM/IMS allows you to change the way FM/IMS chases logical relationships (if the database contains logical relationships).

  1. Type E against the Relationship criteria subset.
  2. Press Enter.

FM/IMS displays the Relationship criteria panel.

From the Relationship criteria panel you are able to:

  • determine the logical relationships FM/IMS is to chase in extracting data.

This is done by typing S against the logical relationship to deselect it. During extract FM/IMS does not pursue this logical relationship.

  • the number of logical relationships chased for each database record.

This is done by specifying a numeric value in 'Max Occurrences to pursue per DB Record' field against each logical relationship. The Default Max relationship occurrences to pursue field is used if a value has not been specified against the logical relationship.

This way FM/IMS can build a small subset of the database for testing purposes.

This relationship diagram shows how the logical relationships for the Suburb segment with a key of FREMANTLE are extracted.

Figure 1. Logical relationships for DJ2E database

    DJ3E                   DJ2E                   DJ1E

 ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─┐       ┌─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─
│                      (2)↓       ↓(4)                      │
  ┌─────────┐            ┌─────────┐            ┌─────────┐
│ │ STREET  │◄ ─ ─ ┐     │ SUBURB  │     ┌ ─ ─ ►│ SHIRE   │ │
  └────┬────┘            └────┬────┘            └────┬────┘
│      │           │          │          │           │      │
       │               ┌──────┴──────┐               │
│      │        (1)│   │             │   │(3)        │      │
  ┌────┴────┐     ┌────┴────┐   ┌────┴────┐     ┌────┴────┐
└─│ INSUB   │     │ LINKSTR │   │ INSHIRE │     │ LINKSUB │─┘
  └─────────┘     └─────────┘   └─────────┘     └─────────┘

Specifying the logical relationships to chase means you can limit the data to be extracted.

For example it is possible to extract the information for FREMANTLE and WEST PERTH from the logically related databases but not include any other suburbs. This is done by not chasing the logical relationships between
  • INSUB and SUBURB
  • LINKSUB and SUBURB
Hence Street names which also exist in other suburbs are not extracted. Also the shires with other suburbs apart from FREMANTLE and WEST PERTH are not extracted.

To ensure that a relationship is not chased, deselect it on the Relationship Criteria panel.