Indexes are mechanisms which will take some effort to store but will help in retrieving the data very fast. Indexes are the database objects which will help database to fetch the query results in high speed manner.

 There are four kinds of Indexes in Teradata based on distribution of data in teradata
 Beside the above there in NOPI ( No Primary Index) in Teradata. 

 AMP Operations of Indexes :

 UPI   : One AMP
NUPI:  All AMP
USI:  Two AMP
NUSI:  All AMP

 In general every table created in teradata will have Primary index which will be created if user provides or dont provides.