11. Maintaining Storage Structures : Modify Procedures : Remodifying B-tree Tables
 
Share this page                  
Remodifying B-tree Tables
If you suspect that the data on the data pages is scattered over several data pages, you can modify the table to B-tree again. You can check this by retrieving the tids as well as the column values, and looking at the pages they reflect.
Remodifying sorts the data and builds the B-tree index, placing like keys on the same data pages, which can slightly reduce the number of disk I/Os required to access the data. For more information, see Tids.
This type of modification is especially useful when the key size is small, the row size is large, and the data has not been appended in sorted order. Remodifying a B-tree is also useful when you have deleted many rows and must reclaim disk space. For more information, see Tracking of Used and Free Pages.