Secondary Index provides an alternate path to the rows of a table.Teradata achieve alternate path by creating sub tables for each secondary index.

Teradata Secondary Index

Secondary Index provides an alternate path to the rows of a table.Teradata achieve alternate path by creating sub tables for each secondary index.

Secondary Index characteristics:
There are two types of Secondary Indexes
Unique Secondary Index (USI): It means that the values for the selected column must be unique.

Non-Unique Secondary Index (NUSI): It means that the values for the selected column can have duplicates.
Value-Ordered NUSI

Covered Query: When all columns in a query can be satisfied by a multi column secondary index subtable it is called a Covered Query.



Drop Secondary Index