Automatic features

Automatic features assist you in managing your database system. They allow your system to perform self-diagnosis and to anticipate problems before they happen by analyzing real-time data against historical problem data. You can configure some of the automatic tools to make changes to your system without intervention to avoid service disruptions.

When you create a database, some of the following automatic features are enabled by default, but others you must enable manually:

Self-tuning memory (single-partition databases only): The self-tuning memory feature simplifies the task of memory configuration. This feature responds to significant changes in workload by automatically and iteratively adjusting the values of several memory configuration parameters and the sizes of the buffer pools, thus optimizing performance. The memory tuner dynamically distributes available memory resources among several memory consumers, including the sort function, the package cache, the lock list, and buffer pools. You can disable self-tuning memory after creating a database by setting the database configuration parameter self_tuning_mem to OFF.

Automatic storage: The automatic storage feature simplifies storage management for table spaces. When you create a database, you specify the storage paths for the default storage group where the database manager places your table space data. Then, the database manager manages the container and space allocation for the table spaces as you create and populate them. You can then also create new storage groups or alter existing ones.
Data compression: Both tables and indexes can be compressed to save storage. Compression is fully automatic; once you specify that a table or index should be compressed using the COMPRESS YES clause of the CREATE TABLE, ALTER TABLE, CREATE INDEX or ALTER INDEX statements, there is nothing more you must do to manage compression. (Converting an existing uncompressed table or index to be compressed does require a REORG to compress existing data). Temporary tables are compressed automatically; indexes for compressed tables are also compressed automatically, by default.
Automatic database backups: A database can become unusable due to a wide variety of hardware or software failures. Ensuring that you have a recent, full backup of your database is an integral part of planning and implementing a disaster recovery strategy for your system. Use automatic database backups as part of your disaster recovery strategy to enable the database manager to back up your database both properly and regularly.
Automatic reorganization: After many changes to table data, the table and its indexes can become fragmented. Logically sequential data might reside on nonsequential pages, forcing the database manager to perform additional read operations to access data. The automatic reorganization process periodically evaluates tables and indexes that have had their statistics updated to see if reorganization is required, and schedules such operations whenever they are necessary.
Automatic statistics collection: Automatic statistics collection helps improve database performance by ensuring that you have up-to-date table statistics. The database manager determines which statistics are required by your workload and which statistics must be updated. Statistics can be collected either asynchronously (in the background) or synchronously, by gathering runtime statistics when SQL statements are compiled. The Db2® optimizer can then choose an access plan based on accurate statistics. You can disable automatic statistics collection after creating a database by setting the database configuration parameter auto_runstats to OFF. Real-time statistics gathering can be enabled only when automatic statistics collection is enabled. Real-time statistics gathering is controlled by the auto_stmt_stats configuration parameter.
Configuration Advisor: When you create a database, this tool is automatically run to determine and set the database configuration parameters and the size of the default buffer pool (IBMDEFAULTBP). The values are selected based on system resources and the intended use of the system. This initial automatic tuning means that your database performs better than an equivalent database that you could create with the default values. It also means that you will spend less time tuning your system after creating the database. You can run the Configuration Advisor at any time (even after your databases are populated) to have the tool recommend and optionally apply a set of configuration parameters to optimize performance based on the current system characteristics.
Health monitor: The health monitor is a server-side tool that proactively monitors situations or changes in your database environment that could result in a performance degradation or a potential outage. A range of health information is presented without any form of active monitoring on your part. If a health risk is encountered, the database manager informs you and advises you on how to proceed. The health monitor gathers information about the system by using the snapshot monitor and does not impose a performance penalty. Further, it does not turn on any snapshot monitor switches to gather information.
Utility throttling: This feature regulates the performance impact of maintenance utilities so that they can run concurrently during production periods. Although the impact policy for throttled utilities is defined by default, you must set the impact priority if you want to run a throttled utility. The throttling system ensures that the throttled utilities run as frequently as possible without violating the impact policy. Currently, you can throttle statistics collection, backup operations, rebalancing operations, and asynchronous index cleanup.