About Data Spreading

Grouping families into hierarchies encourages the use of data spreading. Using data spreading, fields that are common to all families within a branch of the hierarchy can be defined on a family and then spread down to subfamilies. Fields that are specific only to one subfamily can be defined directly at the sublevel. Any fields that are defined for a family will be available for display at all the sublevel. You should not over-use the data-spreading feature. The deeper a family exists in the hierarchy, the more time it takes when querying data from the family because the query must look at many family tables to gather all the information for generating the query results.

Note: If field is baseline then it will not spread the field automatically to the subfamily. Therefore, the spread to subfamily check box will be disabled for all the baseline fields. In addition, the ID Field in the Information tab will also be disabled.

There are three main aspects of field spreading:

Metadata: When a field is spread from one family to another, the metadata (i.e., Field Identification Properties) associated with the root family field is inherited by the subfamily field when the subfamily is created. In other words, the field properties at the target level match the field properties defined at the source level. Most of this information cannot be modified on the family to which the field has been spread. The Caption, Description, and Help Text can be modified. Additionally, the special properties may be editable at the subfamily level, depending on the selected option.
Physical Tablespace: Within the family hierarchy, a table will be created for each family, regardless of its position in the hierarchy.
Behavior: For field-level behavior, you have two options. Within the subfamily, you can choose to:
- Inherit the behavior that are defined for the source family. This is the default condition for spread fields and is indicated by the Allow changing the properties of this field check box in the Configuration Manager. When you select this check box, any changes to field behavior in the source family will be not be applied to the subfamily. If you clear the check box, the subfamily will inherit the field behavior from the source family.
- Define behavior directly within the subfamily by selecting the Allow Changing the properties of this field check box in the Configuration Manager. When you select this option, the field behavior for the subfamily field will be defined directly in the subfamily item. Any behavior that exists in the associated source family will not be applied to the subfamily.

Within the properties of any family field, select the Spread to Sub Families check box. When you do so, all subfamilies created under that family will automatically inherit that field when the subfamily is created.

Note: The changes made to parent family field would be cascaded to all the sub families. If a field is baseline then the field will not be spread to the subfamily in any circumstances. The Spread to subfamily check box will be disabled for all baseline fields.

After a field has been spread, clearing the Spread to Sub Families check box will prevent that field from being spread to additional families but will not remove the field from families to which it has already been spread. The metadata, physical tablespace, and behavior will continue to exist at the subfamily level until they are deleted manually. Clearing a field will, however, break the connection between the source field and the subfamily field, meaning that changes made to the source family field will not be applied at the subfamily level, even if the subfamily field originated through spreading.

Example A: No data spreading applied

Family	Fields
Failure	Failure ID Failure Date Failure Comments
Failure\Equipment Failure	None
Failure\Equipment Failure\Shutdown	None
Failure\Equipment Failure\Leak	Failure ID Failure Date Failure Comments Leak Substance

Example B: Data spreading applied

Family	Fields
Failure	Failure ID Failure Date Failure Comments
Failure\Equipment Failure	Failure ID Failure Date Failure Comments
Failure\Equipment Failure\Shutdown	Failure ID Failure Date Failure Comments
Failure\Equipment Failure\Leak	Failure ID Failure Date Failure Comments Leak Substance

Example A does not use data spreading. Therefore, you need to manually create all the fields in the subfamilies.

Example B uses data spreading. Example B, which uses data spreading, has only four fields as compared to the seven fields created for Example A. Example B, there are no duplicate fields, whereas Example A has three duplicate fields: Failure ID, Failure Date, and Failure Comments. In this example, data spreading multiplied over hundreds of families can help to save administrative time that is required to create and maintain the data fields, and it can help limit the size of the physical database.