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 IBM® Informix® Administrator's Reference.

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

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