org.eigenbase.relopt
Class RelOptQuery

java.lang.Object
  org.eigenbase.relopt.RelOptQuery

public class RelOptQuery
extends Object

A RelOptQuery represents a set of relational expressions which derive from the same select statement.

Version:

$Id: //open/dev/farrago/src/org/eigenbase/relopt/RelOptQuery.java#13 $

Nested Class Summary

static interface

RelOptQuery.DeferredLookup Contains the information necessary to repeat a call to SqlToRelConverter.Blackboard.lookup(int, org.eigenbase.sql2rel.SqlToRelConverter.LookupContext).

Field Summary

static String	correlPrefix Prefix to the name of correlating variables.
(package private) Map<String,RelNode>	mapCorrelToRel Maps name of correlating variable (e.g.
private Map<RelOptQuery.DeferredLookup,String>	mapDeferredToCorrel Maps a from-list expression to the name of the correlating variable which references it.
private int	nextCorrel
private RelOptPlanner	planner

Constructor Summary

RelOptQuery(RelOptPlanner planner)
Creates a query.

Method Summary

RelOptCluster	createCluster(Environment env, RelDataTypeFactory typeFactory, RexBuilder rexBuilder) Creates a cluster.
String	createCorrel() Constructs a new name for a correlating variable.
String	createCorrelUnresolved(RelOptQuery.DeferredLookup deferredLookup) Creates a name for a correlating variable for which no RelNode has been created yet.
static int	getCorrelOrdinal(String correlName) Converts a correlating variable name into an ordinal, unqiue within the query.
Map<RelOptQuery.DeferredLookup,String>	getMapDeferredToCorrel() Returns the map which identifies which correlating variable each RelOptQuery.DeferredLookup will set.
RelNode	lookupCorrel(String name) Returns the relational expression which populates a correlating variable.
void	mapCorrel(String name, RelNode rel) Maps a correlating variable to a RelNode.

Methods inherited from class java.lang.Object

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

Field Detail

correlPrefix

public static final String correlPrefix

Prefix to the name of correlating variables.

See Also:

Constant Field Values

mapDeferredToCorrel

private final Map<RelOptQuery.DeferredLookup,String> mapDeferredToCorrel

Maps a from-list expression to the name of the correlating variable which references it. This is for forward-references, caused when from items have correlating variables. We will later resolve to a RelNode.

mapCorrelToRel

final Map<String,RelNode> mapCorrelToRel

Maps name of correlating variable (e.g. "$cor3") to the RelNode which implements it.

planner

private final RelOptPlanner planner

nextCorrel

private int nextCorrel

Constructor Detail

RelOptQuery

public RelOptQuery(RelOptPlanner planner)

Creates a query.

Parameters:

planner - Planner

Method Detail

getCorrelOrdinal

public static int getCorrelOrdinal(String correlName)

Converts a correlating variable name into an ordinal, unqiue within the query.

Parameters:

correlName - Name of correlating variable

Returns:

Correlating variable ordinal

getMapDeferredToCorrel

public Map<RelOptQuery.DeferredLookup,String> getMapDeferredToCorrel()

Returns the map which identifies which correlating variable each RelOptQuery.DeferredLookup will set.

Returns:

Map of deferred lookups

createCluster

public RelOptCluster createCluster(Environment env,
                                   RelDataTypeFactory typeFactory,
                                   RexBuilder rexBuilder)

Creates a cluster.

Parameters:

env - OpenJava environment

typeFactory - Type factory

rexBuilder - Expression builder

Returns:

New cluster

createCorrel

public String createCorrel()

Constructs a new name for a correlating variable. It is unique within the whole query.

createCorrelUnresolved

public String createCorrelUnresolved(RelOptQuery.DeferredLookup deferredLookup)

Creates a name for a correlating variable for which no RelNode has been created yet.

Parameters:

deferredLookup - contains the information required to resolve the variable later

lookupCorrel

public RelNode lookupCorrel(String name)

Returns the relational expression which populates a correlating variable.

mapCorrel

public void mapCorrel(String name,
                      RelNode rel)

Maps a correlating variable to a RelNode.