IndexDefinition :: unique - UNIQUE option
The unique option prevents the index or collection from storing duplicate key values in an index. Duplicates are detected depending on the data type for the key components and depending on the case sensitive option set for text key components.
Any attempt of storing instances, which create duplicate key values for unique indexes , are denied.
Return value: Success ( bool )
The value is true when the function was executed successfully. Otherwise the value is set to false .
Implementation details
bool
IndexDefinition :: unique ( )
If the function is not called with a valid index definition it throws an exception.