Overview of Informix Warehouse Accelerator

Informix® Warehouse Accelerator is a product that you use to improve the performance of your warehouse queries.

Informix Warehouse Accelerator processes warehouse queries more quickly than the Informix database server. Informix Warehouse Accelerator improves performance while at the same time reduces administration. There are only a few configuration parameters that you need to set to tune query performance. You can install Informix Warehouse Accelerator on same computer as the Informix database server, as shown in the following figure. You can also install Informix Warehouse Accelerator on a separate computer.
Figure 1. Informix Warehouse Accelerator installed on the same computer as the Informix database server.
begin figure description - Architecture of the Informix Warehouse Accelerator with the Informix database server. Shows Informix Warehouse Accelerator installed on the same computer as the Informix database server. You can also install Informix Warehouse Accelerator on a separate computer. - end figure

Informix Warehouse Accelerator is optimal for processing data warehouse queries. The demands of data warehouse queries are substantially different from online transactional processing (OLTP) queries. A typical data warehouse query requires the processing of a large set of data and returns a small result set.

The overhead required to accelerate a query and return a result set is negligible compared with the benefits of using Informix Warehouse Accelerator:
  • Informix Warehouse Accelerator uses a copy of the data.
  • To expedite query processing, the copy of the data is kept in memory in a special compressed format. Advances in compression techniques, query processing on compressed data, and hybrid columnar organization of compressed data enable Informix Warehouse Accelerator to query the compressed data.
  • The data is compressed and kept in memory by Informix Warehouse Accelerator to maximize parallel query processing.

In addition to the performance gain of the warehouse query itself, the resources on the database server can be better used for other types of queries, such as OLTP queries, which perform more efficiently on the database server.

You can use Informix Warehouse Accelerator with a database server that supports a mixed workload OLTP database and a data warehouse database, or use it with a database server that supports only a data warehouse database. However, before you use Informix Warehouse Accelerator you must design and implement a dimensional database that uses a star or snowflake schema for your data warehouse. This design includes selecting the business subject areas that you want to model, determining the granularity of the fact tables, and identifying the dimensions and hierarchies for each fact table. Additionally, you must identify the measures for the fact tables and determine the attributes for each dimension table.

The following figure shows a sample snowflake schema with a fact table and multiple dimension tables.
Figure 2. A sample snowflake schema that has the DAILY_SALES table as the fact table.
Begin figure description - The figure shows the DAILY_SALES fact table in the center of the figure. This fact table is linked to five dimension tables: STORE, PERIOD, PRODUCT, PROMOTION, and CUSTOMER. The STORE table is linked to the CITY table. The CITY table is linked to the REGION table. The PERIOD table is linked directly to the MONTH and QUARTER tables. The PRODUCT table is linked directly to the BRAND and PRODUCT_LINE tables. The PROMOTION table is not linked to any other tables. The CUSTOMER table is linked directly to three tables: CONTACT, ADDRESS, and DEMOGRAPHICS. - end figure

An accelerator server is an installation of Informix Warehouse Accelerator.

The accelerator server contains one or more accelerators. An accelerator is a logical entity that contains information for a connection from the database server to the accelerator server and for the data marts associated with that connection. A data mart specifies the collection of tables from a database that are loaded into an accelerator and the relationships, or references, between these tables. After you create a data mart, information about the data mart is sent to the database server in the form of a special view called an accelerated query table or AQT. The database server uses the AQTs to determine which queries or query blocks can be accelerated.

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