You can optimize and organize the DB2® database with the DB2 commands to reduce data access time and retrieval time.
DB2 uses a sophisticated set of algorithms to optimize the access to data stored in a database. These algorithms depend upon many factors, including the organization of the data in the database and the distribution of that data in each table. The database manager maintains a set of statistics to represent the distributed data.
A directory server creates a number of indexes for tables in the database. These indexes minimize the time that is required to access data and locate a particular row in a table.
In a read-only environment, the distribution of the data does not change much. With updates and additions to the database, it is not uncommon for the distribution of the data to change significantly. Similarly, it is possible for data in tables to become ordered in an inefficient manner.
To remedy these issues, DB2 provides tools to optimize the data access by updating the statistics. DB2 also provides tools to reorganize the data within the tables of the database.