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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.
Improving individual query performanceYou can test, monitor, and improve queries.
Update statistics when they are not generated automaticallyThe UPDATE STATISTICS statement updates the statistics in the system catalog tables that the optimizer uses to determine the lowest-cost query plan.
Update statistics in parallel on very large databasesIf you have an extremely large database and indexes are fragmented, UPDATE STATISTICS LOW can automatically run statements in parallel.

Update statistics in parallel on very large databases

If you have an extremely large database and indexes are fragmented, UPDATE STATISTICS LOW can automatically run statements in parallel.

To enable statements to automatically run in parallel, you must run UPDATE STATISTICS LOW with the PDQ priority set to a value that is between 1 and 10. If the PDQ priority is set to 1, 10 percent of the index fragments are analyzed at one time for the current table. If the PDQ priority is set to 5, 50 percent of the index fragments are analyzed at one time for the current table. If the PDQ priority is set to 10, all fragments are analyzed at one time for the current table. (If the PDQ priority is set to a value that is higher than 10, HCL OneDB™ operates as if the PDQ priority is set to 10, analyzing all fragments at one time for the current table.)

If you run UPDATE STATISTICS MEDIUM or HIGH, you can set the PDQ priority to a value that is higher than 10. Because the UPDATE STATISTICS MEDIUM and HIGH statements perform a large amount of sorting operations, increasing the PDQ priority to a value that is higher than 10 provides additional memory than can improve the speed of the sorting operations.

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