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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.
Types of optimizer directives that are supported in SQL statementsDirectives that are in SQL statements are embedded in queries. These directives include access-method directives, join-order directives, join-plan directives, and optimization-goal directives.
Star-join directivesStar-join directives can specify how the query optimizer joins two or more tables, among which one or more dimension tables have foreign-key dependencies on one or more fact tables.

Star-join directives

Star-join directives can specify how the query optimizer joins two or more tables, among which one or more dimension tables have foreign-key dependencies on one or more fact tables.

The following directives can influence the join plan for tables that logically participate in a star schema or in a snowflake schema:

FACT
The optimizer considers a query plan in which the specified table is a fact table in a star-join execution plan.
AVOID_FACT
The optimizer does not consider a star-join execution plan that treats the specified table (or any of the tables in the list of tables) as a fact table.
STAR_JOIN
The optimizer favors a star-join execution plan, if available.
AVOID_STAR_JOIN
The optimizer chooses a query execution plan that is not a star-join plan.

These star-join directives have no effect unless the parallel database query feature (PDQ) is enabled.

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