GENERATE STATISTICS command

Although the Netezza Performance Server for Cloud Pak for Data and Netezza Performance Server for Cloud Pak for Data System system automatically maintains certain statistics, you might want to run GENERATE STATISTICS command periodically, or in the following cases:

• When you have significantly changed the nature of your database, that is, increased or decreased the number of distinct values, expanded or reduced the min/max values on joinable or groupable fields, or increased or decreased the size of your database.
• When you have static tables that you intend to keep for a long time
• When you have queries that involve three or more joins
• When you change your tables and observe slower performance when querying the updated tables
• When you have columns that are used in WHERE, SORT, GROUP BY, or HAVING clauses
• When you have temporary tables that contain many rows and that are used in JOIN clauses