The IBM® PureData® System for Analytics, powered by Netezza® technology (“IBM Netezza”), is a data warehouse appliance that features a purpose-built analytics engine. Netezza generates a query plan for all queries that run on the system. The query plan describes the optimal execution query path as determined by the query optimizer component, which relies on statistics that are available about the database objects that are involved in the query.
The Netezza query optimizer is a cost-based optimizer; that is, it determines the cost for the various execution alternatives and chooses the path with the least cost as the optimal execution path for a particular query. The execution plan with the lowest cost among all candidate plans is considered the most efficient. However, in certain situations the Netezza optimizer might not provide the best query plan that leads to the best query performance.
This IBM Redbooks® Analytics Support Web Doc describes some Postgres parameters that can be used to influence the Netezza query optimizer and improve the query performance.
This document is intended for Netezza administrators and application users who run SQL queries on the Netezza database. This document applies to IBM PureData® System for Analytics (powered by Netezza technology) V7.0.3 and higher.
The material included in this document is in DRAFT form and is provided 'as is' without warranty of any kind. IBM is not responsible for the accuracy or completeness of the material, and may update the document at any time. The final, published document may not include any, or all, of the material included herein. Client assumes all risks associated with Client's use of this document.