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Rule Documentation

All Packages - Package Correct Operatorgraph - Package Logical Optimization - Package Physical OptimizationFRAMES - NO FRAMES

Rule Package Logical Optimization

Short Description:

Logical optimization aims to reorganize the operator graph into an equivalent operator graph, which generates the same output for any input as the original operator graph, in order to optimize the execution time of query evaluation.

Rules:

Optimizing Join Order: The join order is optimized by etimating the cardinality of the result of single joins and first joining those, which have the estimated smallest number of intermediate results.

Variable Propagation: This rule implements variable propagation.

Constant Propagation: This rule implements constant propagation.

Factor out AND in Filter: All AND (&&) -operations in filter expressions are factored out.

Push Filter: Filter operators never increase, but reduce the number of intermediate results in most times. Thus, it is important for the performance to evaluate a filter expression as early as possible. This rule pushes a filter operator upwards in the operator graph whenever possible.

Constant Propagation of filter with ORs: This rule implements constant propagation for a set of constants.

Binary Join: This transformation rule optimizes the join order for the Stream approach and generates only binary joins.


All Packages - Package Correct Operatorgraph - Package Logical Optimization - Package Physical OptimizationFRAMES - NO FRAMES