Package org.apache.flink.optimizer.traversals

This package contains the various traversals over the program plan and the optimizer DAG (directed acyclic graph) that are made in the course of the optimization.

The traversals are mostly implemented as a Visitor that traversed the program flow.

Class Summary

Class	Description
BinaryUnionReplacer	A traversal that collects cascading binary unions into a single n-ary union operator.
BranchesVisitor	This traversal of the optimizer DAG computes the information needed to track branches and joins in the data flow.
GraphCreatingVisitor	This traversal creates the optimizer DAG from a program.
IdAndEstimatesVisitor	This traversal of the optimizer DAG assigns IDs to each node (in a pre-order fashion), and calls each node to compute its estimates.
InterestingPropertyVisitor	Visitor that computes the interesting properties for each node in the optimizer DAG.
PlanFinalizer	This visitor traverses the selected execution plan and finalizes it: The graph of nodes is double-linked (links from child to parent are inserted).
RangePartitionRewriter
StaticDynamicPathIdentifier	A traversal that goes over the program data flow of an iteration and makes the nodes that depend on the partial solution (the data set recomputed in each iteration) as "dynamic" and the other nodes as "static".
StepFunctionValidator	A traversal that checks if the Workset of a delta iteration is used in the data flow of its step function.
UnionParallelismAndForwardEnforcer	Enforces that all union nodes have the same parallelism as their successor (there must be only one!) and that the union node and its successor are connected by a forward ship strategy.