Configuring the Db2 database manager with configuration parameters
The disk space and memory that is allocated by the database manager based on default values of the parameters might be sufficient to meet your needs. However, in some situations you might not be able to achieve maximum performance by using these default values.
About this task
- Large databases
- Large numbers of connections
- High-performance requirements for a specific application
- Unique query or transaction loads or types
Each transaction processing environment is unique in one or more aspects. These differences can have a profound impact on the performance of the database manager when you are using the default configuration. For this reason, you are advised to tune your configuration for your environment.
A good starting point for tuning your configuration is to use the Configuration Advisor or the AUTOCONFIGURE command. These tools generate values for parameters based on your responses to questions about workload characteristics.
Some configuration parameters can be set to AUTOMATIC, allowing the database manager to automatically manage these parameters to reflect the current resource requirements. To turn off the AUTOMATIC setting of a configuration parameter while you are maintaining the current internal setting, use the MANUAL keyword with the UPDATE DATABASE CONFIGURATION command. If the database manager updates the value of these parameters, the GET DB CFG SHOW DETAIL and GET DBM CFG SHOW DETAIL commands show the new value.
Parameters for an individual database are stored in a configuration file named SQLDBCONF. This file is stored along with other control files for the database in the SQLnnnnn directory, where nnnnn is a number that is assigned when the database was created. Each database has its own configuration file, and most of the parameters in the file specify the amount of resources that are allocated to that database. The file also contains descriptive information, and flags that indicate the status of the database.
If you edit db2systm, SQLDBCON, or SQLDBCONF by using a method other than the methods provided by the database manager, you might make the database unusable. Do not change these files by using methods other than the methods documented and supported by the database manager.
In a partitioned database environment, a separate SQLDBCONF file exists for each database partition. The values in the SQLDBCONF file might be the same or different at each database partition. However, the recommendation is that in a homogeneous environment, the configuration parameter values must be the same on all database partitions. Typically, there might be a catalog node that needs different database configuration parameters setting, while the other data partitions have different values again, depending on their workstations types, and other information.