Define relationships for a measure

After you select dimensions for a measure, you must define relationships. Relationships help define context for the measure.

There are three types of relationships:

• Key relationship - You can relate to a dimension key field using a source data item field. This establishes the relationship between the measure record and the selected dimension.

• Dimension link relationship - You can relate a dimension using a linked dimension. This adds the linked dimension reference in the measure table. For example, your source data defines values with respect to equipment. However, you want to have the Site definition with your measure data. The Equipment dimension contains a dimension link to Site. This allows you to add the Site dimension to the measure data and use the linked dimension for site defined in the Equipment dimension.

• Time-based relationship - You can provide a time-based relation for a dimension that has a time-slice configured. The system automatically maps to the dimension using the data source DateTime field that you define for aggregate calculation.

For example, you want to have Shift context on a Historian aggregate value. If Shift is defined as a time-slicing dimension, you can use a time relationship to relate the timestamp of the Historian data to the time-slices defined by the Shift dimension.

You can either provide a dimension link relationship or you must provide a relationship for all the key fields of a dimension. For example, if you select a dimension that has four key fields that form a composite key, then you must provide a relationship for all the four key fields. However, you can provide only one time-based relationship for a key field out of the four key fields.

If you are providing a dimension link relationship, then you do not need to provide a mapping for all the other key fields of the dimension.

Define a relationship for a measure

1. Open the AVEVA BI Gateway Model Builder.

2. Click the Add icon in the Fast Action Buttons menu and then click the Measure icon. A new measure is added in the AVEVA BI Gateway model with a default name and the Measure editor appears in the right pane.

3. Click the Edit Calculations button. The Context & Calculations page appears.

4. In the Context & Calculations page, click a required aggregate calculation.

5. Click the Context Relationships button. The Context page appears.

6. In the Relationships grid, do the following:

   The Dimensions column shows the alias names of dimensions that you select in the Context tab. One row is added for each key field of a dimension.

   The References column shows:

   • All the key fields (represented by a Key icon) of the current dimension.

   • Dimension links (represented by a Link icon) of the dimensions that you select in the Context tab, that reference the current dimension. If you select the dimension link option for a dimension, then all other rows for the dimension are unavailable.

   • If the corresponding dimension has time-slicing configured, then the dimension column also shows the "TIME" option (represented by a Clock icon).

     1. Under the References column, click the required option.

     2. The Mappings column shows any one of the following depending on the option you select under the References column:

        • If you select a dimension key, then it shows the fields of the source data item that is used for measure calculation. You must select the field from the source data item which maps to the selected key field of the dimension.

        • If you select a dimension link, then it shows the dimension of the selected dimension link.

        • If you select the TIME option, then the Mappings field is unavailable. The system automatically maps the dimension to the data source DateTime field that you define for aggregate calculation.

        • Click the required option.

     Note: If you select a dimension key field under the References column, then you can map the dimension key field to a constant value. Ensure that the dimension key field type is compatible with the constant type.

7. Click Save.