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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.
Indexes and index performance considerationsHCL OneDB™ provides several types of indexes. Some performance issues are associated with indexes.
Managing indexesAn index on the appropriate column can save thousands, tens of thousands, or in extreme cases, even millions of disk operations during a query. However, indexes entail costs.
Unclaimed index spaceA background thread, the B-tree scanner, identifies an index with the most unclaimed index space. Unclaimed index space degrades performance and causes extra work for the server. When an index is chosen for scanning, the entire leaf of the index is scanned for deleted (dirty) items that were committed, but not yet removed from the index. The B-tree scanner removes these items when necessary.

Unclaimed index space

A background thread, the B-tree scanner, identifies an index with the most unclaimed index space. Unclaimed index space degrades performance and causes extra work for the server. When an index is chosen for scanning, the entire leaf of the index is scanned for deleted (dirty) items that were committed, but not yet removed from the index. The B-tree scanner removes these items when necessary.

The B-tree scanner allows multiple threads.

Use the BTSCANNER configuration parameter to specify the number of B-tree scanner threads to start and the priority of the B-tree scanner threads when the database server starts. For details, see the HCL OneDB™ Administrator's Reference.

You can invoke the B-tree scanner from the command line.

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