Summary of Hash Index Functions - Teradata Database

Teradata Database Design

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Summary of Hash Index Functions

A hash index always has at least one of the following functions.

  • Replicates all, or a vertical subset, of a single base table and partitions its rows with a user‑specified partition key column set, such as a foreign key column to facilitate joins of very large tables by hashing them to the same AMP.
  • Provides an access path to base table rows to complete partial covers.
  • The AMP software updates hash indexes automatically, so the only task a DBA must perform is to keep the statistics on hash index or base table columns current (see “Collecting Statistics on Hash Index Columns” on page 560).