LUPOSDATE Logo

Rule Documentation

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

Rule Physical Optimization

Short Description:

Physical optimization aims to choose the algorithm with the best estimated execution times in the context of the operator for each operator in the operator graph.

Long Description:

This transformation rule considers several aspects.

This transformation rule chooses the concrete algorithm for a logical operator according to the option, if the memory-based variant of our prototype is used (where all the data remains in the main memory), or the disk-based variant is used (where the indices and the intermediate results on demand are stored on disk).

Furthermore, this transformation rule considers specific preferences of the user for specific algorithms. This means that the user can specify (e.g. per command line option) to use e.g. the DBMergeSortedBagMergeJoin as default Join algorithm, which is considered in this transformation rule.

For the Sort operator, the transformation rule checks, whether the intermediate result is already sorted in the correct way (or can be retrieved in a sorted way), such that the Sort operator can be left out.

For the Distinct operator, this transformation rule checks whether or not the intermediate data is sorted in the correct way, such that the effcient SortedDataDistinct operator can be used.

If the RDF3X - Presorting or Hexastore - Presorting approaches are used, then this transformation rule checks, whether or not the fast sorting capability of these approaches can be used in order to use more MergeJoinWithoutSorting/MergeJoinSort operators, the Sort operator can be replaced or SortedDataDistinct can be used.


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