Data marts and AQTs

For efficient query processing, the accelerator server must have its own copy of the data. The data is stored in logical collections of related data, or data marts. A data mart specifies the collection of tables that are loaded into an accelerator and the relationships, or references, between these tables.

A data mart definition is an XML file that contains information about the tables used by your warehouse queries. The information includes the tables and columns within the table that are included in the data mart. The information also specifies how the tables and columns are related to each other. The XML file that contains the data mart definition does not contain any actual user data. You can create a data mart definition by analyzing the workload for your existing warehouse queries against your existing warehouse schema. Alternatively, you can create a data mart definition by using IBM® OpenAdmin Tool (OAT) for Informix® or Informix Smart Analytics Optimizer Studio.

When a data mart is created, information about the data mart is sent to the Informix database server in the form of a special view referred to as an accelerated query table or AQT. The information in the AQTs is used by the database server to determine which queries or query blocks can be processed by Informix Warehouse Accelerator.