Home
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.
Administrator's GuideThe HCL OneDB™ Administrator's Guide provides the information required to administer HCL OneDB™.
Disk, memory, and process management
Shared memoryThese topics describe the content of database server shared memory, the factors that determine the sizes of shared-memory areas, and how data moves into and out of shared memory.
Virtual portion of shared memoryThe virtual portion of shared memory is expandable by the database server and can be paged out to disk by the operating system.
Data-distribution cacheThe database server uses distribution statistics generated by the UPDATE STATISTICS statement in the MEDIUM or HIGH mode to determine the query plan with the lowest cost.

Data-distribution cache

The database server uses distribution statistics generated by the UPDATE STATISTICS statement in the MEDIUM or HIGH mode to determine the query plan with the lowest cost.

When the database server accesses the distribution statistics for a specific column the first time, it reads the distribution statistics from the sysdistrib system catalog table on disk and stores the statistics in the data-distribution cache. These statistics can then be read for the optimization of subsequent queries that access the column.

Performance improves if these statistics are efficiently stored and accessed from the data-distribution cache. You can configure the size of the data-distribution cache with the DS_HASHSIZE and DS_POOLSIZE configuration parameters. For information about changing the default size of the data-distribution cache, see the topics about queries and the query optimizer in your HCL OneDB™ Performance Guide.

Have feedback?
Google Analytics is used to store comments and ratings. To provide a comment or rating for a topic, click Accept All Cookies or Allow All in Cookie Preferences in the footer of this page.