com.bigdata.rdf.sparql.ast.optimizers

Class ASTStaticJoinOptimizer

java.lang.Object

com.bigdata.rdf.sparql.ast.optimizers.ASTStaticJoinOptimizer

All Implemented Interfaces:

IASTOptimizer

public class ASTStaticJoinOptimizer
extends Object
implements IASTOptimizer

This is an AST optimizer port of the old "static" optimizer - DefaultEvaluationPlan2. This optimizer uses range counts and simple shared variable heuristics to order the statement patterns within a particular join group. This optimizer extends the old static optimizer in that child join groups consider the ordering of statement patterns in their parent and ancestors when deciding how their own order.

We want to optimize all JoinGroupNodes recursively, from the top down. This is because the join group needs to take into account its ancestral join ordering when deciding its own join ordering. A statement pattern with a shared variable with the ancestral groups should be preferred over one with no shared variables.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	ASTStaticJoinOptimizer.Annotations

Field Summary

Fields

Modifier and Type	Field and Description
static org.apache.log4j.Logger	log

Constructor Summary

Constructors

Constructor and Description
ASTStaticJoinOptimizer()

Method Summary

Methods

Modifier and Type	Method and Description
QueryNodeWithBindingSet	optimize(AST2BOpContext context, QueryNodeWithBindingSet input) Optimize the AST.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

log

public static final org.apache.log4j.Logger log

Constructor Detail

ASTStaticJoinOptimizer

public ASTStaticJoinOptimizer()

Method Detail

optimize

public QueryNodeWithBindingSet optimize(AST2BOpContext context,
                               QueryNodeWithBindingSet input)

Description copied from interface: IASTOptimizer

Optimize the AST.

Specified by:

optimize in interface IASTOptimizer

Parameters:

context - The evaluation context.

input - The input to the optimizer, consisting of a queryNode and input binding set.

Returns:

An instance of type QueryNodeWithBindingSet.