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AdministeringIn addition to administering the database server, you can tune performance, replicate data, and archive data.
System administrationThese topics contain concepts, procedures, and reference information for database and database server administrators to use for managing and tuning HCL OneDB™ database servers.
Performance GuideThe HCL OneDB™ Performance Guide describes how to configure and operate your HCL OneDB™ database server to improve overall system throughput and to improve the performance of SQL queries.
Effect of configuration on CPU utilizationThe combination of operating-system and HCL OneDB™ configuration parameters can affect CPU utilization. You can change the settings of the HCL OneDB™ configuration parameters that directly affect CPU utilization, and you can adjust the settings for different types of workloads.
Configuration parameters and environment variables that affect CPU utilizationSome configuration parameters and environment variables affect CPU utilization. You might need to adjust the settings of these parameters and variables when you consider methods of improving performance.
Optimizing access methodsThe OPTCOMPIND configuration parameter helps the query optimizer choose an appropriate access method for your application. When the optimizer examines join plans, OPTCOMPIND indicates the preferred method for performing the join operation for an ordered pair of tables.
Setting the value of OPTCOMPIND within a sessionYou can set or change the value of OPTCOMPIND within a session for different kinds of queries. To do this, use the SET ENVIRONMENT OPTCOMPIND statement, not the OPTCOMPIND configuration parameter or the OPTCOMPIND environment variable.

Setting the value of OPTCOMPIND within a session

You can set or change the value of OPTCOMPIND within a session for different kinds of queries. To do this, use the SET ENVIRONMENT OPTCOMPIND statement, not the OPTCOMPIND configuration parameter or the OPTCOMPIND environment variable.

For a DSS query, you should set the value of OPTCOMPIND to 2 or 1, and you should be sure that the isolation level is not set to Repeatable Read. For an OLTP query, you could set the value to 0 or 1 with the isolation level not set to Repeatable Read.

The value that you enter using the SET ENVIRONMENT OPTCOMPIND command takes precedence over the default setting specified by the OPTCOMPIND environment variable or by the OPTCOMPIND configuration parameter in the ONCONFIG file. The default OPTCOMPIND setting is restored when the routine that issued the SET ENVIRONMENT OPTCOMPIND statement exits, or until the same routine resets the value of OPTCOMPIND to the system default by issuing the following statement:

SET ENVIRONMENT OPTCOMPIND DEFAULT;

No other user sessions or routines are affected by SET ENVIRONMENT OPTCOMPIND statements that you execute, because their scope is local to the routine in which they are issued, rather than the entire session.