Package se.liu.ida.hefquin.engine.queryproc.impl.loptimizer.heuristics
package se.liu.ida.hefquin.engine.queryproc.impl.loptimizer.heuristics
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ClassesClassDescriptionBase class for heuristics that use cardinality estimates to decide on a join order for the subplans of a multiway join or a binary join.This class is an implementation of
CardinalityBasedJoinOrderingBasethat uses cardinality requests.Pushes filter conditions as much as possible towards the leaf nodes of a given logical plan.Implement a greedy algorithm to determine the join order of sub-plans.Merges subplans that consists of multiple requests to the same federation member if such a merge is possible.Pushes project operators as much as possible towards the leaf nodes of a given logical plan.In cases in which there are unions with requests under joins (which may happen only if we do not useUnionPullUp, this heuristics turns the requests into gpAdd operators with the previous join arguments as subplans.Removes every subplan that is guaranteed to produce an empty result according to the cardinality estimate that is determined for it.Pulls up all (multiway) union operators in the given plan as high up as possible.