TeraTeam UK Teradata DBA Definition
Statistics :
Statistics within the Teradata RDBMS are used by the cost-based Optimiser to establish the demographics of the data held in tables referenced in a SQL Query. This enables the optimiser to derive the optimum method of retrieving, distributing and joining the data in order to avoid data skew and thus ensure system resources are best utilised.
Ideally, Statistics should be collected when the data demographics change i.e. when data is loaded or deleted, and should generally be collected on the index columns of the referenced tables and those used within join clauses or where conditions.
