The standard table index for D365 FO tables, as used by Data modeling studio, consists of these fields: RecId and RecVersion. You can select additional primary indexes, if available for the data set table. These additional primary indexes are then used as well by Data modeling studio.

Note: To use additional indexes, the table system fields must be added as well. If you select an additional index and the 'Add system fields' field was set to 'No', this field is automatically set to 'Yes'.

Standard procedure

1.	Go to Data modeling studio > Data modeling studio > Data sets.
2.	In the list, click the link of the desired data set.
3.	On the Action Pane, click Create.
4.	Click Index.
5.	On the dialog, all indexes, as defined for the data set table, are shown.
	In the list, find the index that you want to use for the data set.
6.	For each index that you want to use, select the 'Selected' check box.
7.	Click OK.
8.	An index consists of one or more fields. To use an index, you must add the index fields to the data set. If you select an index, and the index field is not added to the data set, you get a message to add the index field to the data set.
	Click Yes.