Which indexes are used to control data accessibility in Teradata?

Primary and Secondary Indexes are used to control data accessibility in Teradata because they directly influence how data is retrieved and organized within the database.

Primary Indexes are essential for distributing data across the Teradata system by determining how data is stored across the nodes. The selection of a Primary Index affects the data's retrieval efficiency, as it ensures that rows are stored in a way that optimizes access paths based on this indexing. When queries are executed, the Primary Index provides a direct path to the data, making retrieval faster and more efficient.

Secondary Indexes, on the other hand, are utilized to further optimize data access by providing additional pathways to data based on non-primary key columns. They enable faster retrieval when queries involve different columns that are not part of the Primary Index. By allowing multiple points of access to the underlying data, Secondary Indexes enhance query performance and flexibility.

In summary, Primary and Secondary Indexes are fundamental to data accessibility in Teradata, as they dictate how data is stored and accessed, ultimately affecting performance efficiency.