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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.

Optimizing access methods

The 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.

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If OPTCOMPIND is equal to 0, the optimizer gives preference to an existing index (nested-loop join) even when a table scan might be faster. If OPTCOMPIND is set to 1 and the isolation level for a given query is set to Repeatable Read, the optimizer uses nested-loop joins.

When OPTCOMPIND is equal to 2, the optimizer selects a join method based on cost alone even though table scans can temporarily lock an entire table. For more information about OPTCOMPIND and the different join methods, see Effect of OPTCOMPIND on the query plan.

To set the value for OPTCOMPIND for specific applications or user sessions, set the OPTCOMPIND environment variable for those sessions. Values for this environment variable have the same range and semantics as for the configuration parameter.