OLAP Setup and User's Guide

Using Table Spaces

Creating appropriate table spaces and mapping tables to them can have a significant effect on DB2 performance.

DB2 relational tables are created in table spaces. A table space is a storage model that provides a level of indirection between a database and the tables that are stored within the database.

Table spaces map the logical tables to the physical devices. Using table spaces to optimize the mapping of data onto devices can significantly improve performance, and can result in a more flexible configuration and increased integrity.

Defining Storage Architecture on UNIX and Windows NT Servers

When you design storage architecture for DB2 OLAP Server on UNIX and Windows NT servers, follow these guidelines:

• Use multiple table spaces. Each table space should contain multiple containers where each container is a separate physical device. Use database-managed storage (DMS) table spaces.
• Put the fact tables in a different table space than the fact table indexes.
• Put the key and dimension tables in a different table space than the key and dimension table indexes.

The rsm.cfg configuration file has two parameters that let you control how DB2 OLAP Server uses table spaces on Windows NT and UNIX :

• The TABLESPACE parameter specifies the table spaces for the key and dimension tables and indexes that DB2 OLAP Server manages. The parameter appends the clause that you enter here to a DB2 CREATE TABLE command. You can specify the INDEX IN clause of the CREATE TABLE statement. By specifying this clause, you instruct DB2 OLAP Server to store tables in one table space and indexes in another. For example:

  TABLESPACE=IN TSMAIN INDEX IN TSMAINI
  

• The FACTS parameter specifies the table spaces for the fact tables and indexes. The parameter also lets you specify the INDEX IN clause of the CREATE TABLE statement. By specifying this clause, you instruct DB2 OLAP Server to store tables in one table space and indexes in another. For example:

  FACTS=IN TSFACT INDEX IN TSFACT1
  

See the DB2 Administration Guide for more information about designing, creating, and managing table spaces.