com.bigdata.rdf.sparql.ast.optimizers

Class ASTQueryHintOptimizer

java.lang.Object

com.bigdata.rdf.sparql.ast.optimizers.ASTQueryHintOptimizer

All Implemented Interfaces:

IASTOptimizer

public class ASTQueryHintOptimizer
extends Object
implements IASTOptimizer

Query hints are identified applied to AST nodes based on the specified scope and the location within the AST in which they are found. Query hints recognized by this optimizer have the form:

 scopeURL propertyURL value
 

Where scope is any of the QueryHintScopes; and
Where propertyURL identifies the query hint;
Where value is a literal.

Once recognized, query hints are removed from the AST. All query hints are declared internally using interfaces. It is an error if the specified query hint has not been registered with the QueryHintRegistry, if the IQueryHint can not validate the value, if the QueryHintScope is not legal for the IQueryHint, etc.

For example:

 ...
 {
    # query hint binds for this join group.
    hint:Group hint:com.bigdata.bop.PipelineOp.maxParallel 10
    
    ...
    
    # query hint binds for the next basic graph pattern in this join group.
    hint:Prior hint:com.bigdata.relation.accesspath.IBuffer.chunkCapacity 100
    
    ?x rdf:type foaf:Person .
 }
 

Author:

Bryan Thompson

See Also:

QueryHints, QueryHintScope

Constructor Summary

Constructors

Constructor and Description
ASTQueryHintOptimizer()

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

Constructor Detail

ASTQueryHintOptimizer

public ASTQueryHintOptimizer()

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.