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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.
Optimizer directivesOptimizer directives are comments that tell the query optimizer how to execute a query. You can use optimizer directives to improve query performance.
Guidelines for using directivesGuidelines for directives include frequently analyzing the effectiveness of the query and using negative directives.

Guidelines for using directives

Guidelines for directives include frequently analyzing the effectiveness of the query and using negative directives.

Consider the following guidelines:

Examine the effectiveness of a particular directive frequently to make sure it continues to operate effectively. Imagine a query in a production program with several directives that force an optimal query plan. Some days later, users add, update, or delete a large number of rows, which changes the nature of the data so much that the once optimal query plan is no longer effective. This example illustrates how you must use directives with care.
Use negative directives (such as AVOID_NL, AVOID_FULL, and so on) whenever possible. When you exclude a behavior that degrades performance, you rely on the optimizer to use the next-best choice rather than attempt to force a path that might not be optimal.