| 摘要 |
Database tables can have different types of database indices defined for the database tables and different numbers of database indices. The efficiency of reading the indexes can vary with the different profiles of the indexes, which impacts the costs of access plans that use the indexes. Weights can be predefined to reflect the relative efficiencies of the different characteristics. Costs can be computed in accordance with a variety of techniques (e.g., based on edge traversals). The weights can be predefined to reduce costs, increase costs, or a combination thereof. A database management application or associated application or program can also refine or revise these weights based on statistical data gathered about the operation of the database and/or heuristics that are developed based on observations/research. The corresponding weights can be adjusted accordingly.
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