17.00 - 17.05 - Collecting Statistics on Join Index Columns - Advanced SQL Engine - Teradata Database

Teradata Vantage™ - Database Administration

Product
Advanced SQL Engine
Teradata Database
Release Number
17.00
17.05
Published
June 2020
Language
English (United States)
Last Update
2021-01-22
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  • For non-sparse join and hash indexes, the Optimizer inherits the row count and all histograms from the base tables. Teradata recommends that you collect statistics on base tables only and not on the non-sparse join or the hash indexes.
  • For sparse join indexes, Teradata recommends that you collect statistics on base tables and sparse join indexes separately.
  • For non-compressed join indexes, the Optimizer performs all-AMP sampling to estimate the join index row count accurately.
  • For compressed sparse join indexes, Teradata recommends that you collect PI statistics. The All-AMP random sampling that the Optimizer performs may not reflect an accurate row count because of the compression.