Specifies the type of index. The types are:
Not unique: Indicates that the table can contain multiple rows with the same value of the index key.
Encoded Vector (Not unique): Indicates that the resulting index is an encoded vector index. Encoded vector indexes (EVIs) keep track of the distinct values that can be found in the key columns of a table. EVIs can improve data warehouse performance queries as well as business applications queries. An EVI cannot be used to ensure any expected ordering of records and cannot be used for positioning of an open data path.
Unique: Prevents the table from containing two or more rows with the same value of the index key.
Unique where not null: Prevents the table from containing two or more rows with the same non-null value of the index key. Multiple rows with null values are allowed.