Index attributes for an external class can be configured in one of two ways:
For the first option, one Integer data type attribute must have the Unique value selected in the Index drop-down menu. Only one attribute that only uses positives values can have this setting. This attribute must be linked to a column in the external database table that has unique integer formatted data.
Unique attributes for external classes cannot be modified in the WorkView clients.
In order to extend an external class, an index must be configured.
For the second option, you can configure a unique index as a Composite Key where values from multiple attributes are used to uniquely identify objects. To accomplish this, any attribute you would like to use as part of the Composite Key must be configured with the Composite Key Component value in the Index drop-down list.
Once a composite key ID has been generated, the Composite Key Value configuration cannot be edited.
For WCF classes, the attributes that are used for the Unique Index or Composite Keys need to be mapped to input parameters on the Web Service being used for the class.
Attributes configured as Composite Key Components for external classes cannot be modified in the WorkView clients.
Defining a Composite Key unique index for an external class imposes some additional overhead when working with these objects. If a unique integer key is available for the external data, this should be used as the index.
External classes configured with the Unity Script class type will not have the Composite Key Component option available.
If you execute a filter on an composite-key based external class and include ObjectID as a display column, the filter will list valid ObjectIDs for each result. If an object already has a local ObjectID generated for its composite key values, it will be displayed, otherwise a new ObjectID will be generated and displayed.
In Filter Result of Standard Class with a related ODBC External Class having composite key, to fetch a large number of records at a time from external table, the number of records per Database Call equals to the fixed batch size of 500 divided by the number of composite keys.
In addition, all attribute data types should match the data format existing in the database column to which they are linked. See Configuring External Class Attributes for more information.