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Database Systems: Concepts, Design and Applications by S. K. Singh

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11.8. Structure of Query Evaluation Plans

An evaluation plan is used to define exactly what algorithm should be used for each operation and how the execution of the operations should be coordinated. So far we have discussed mainly two basic approaches to choosing an execution (action) plan namely, (a) heuristic optimization and (b) cost-based optimization. Most query optimisers combine the elements of both these approaches. Fig. 11.9 shows one of the possible evaluation plans.

Fig. 11.9. An evaluation plan

11.8.1. Query Execution Plan

The query execution plan may be classified into the following:

  • Left-deep (join) tree query execution plan. ...

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