net.sf.saffron.opt
Class VolcanoQuery

java.lang.Object
  |
  +--net.sf.saffron.opt.VolcanoQuery

public class VolcanoQuery

extends Object

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

Field Summary

static String	correlPrefix Prefix to the name of correlating variables.
(package private) HashMap	mapCorrelToRel Maps name of correlating variable (e.g.
HashMap	mapDeferredToCorrel Maps a from-list expression to the name of the correlating variable which references it.
private int	nextCorrel
private VolcanoPlanner	planner

Constructor Summary

VolcanoQuery()

VolcanoQuery(VolcanoPlanner planner)

Method Summary

VolcanoCluster	createCluster(Environment env, SaffronTypeFactory typeFactory)
String	createCorrel() Constructs a new name for a correlating variable.
String	createCorrelUnresolved(Object deferredLookup) Creates a name for a correlating variable for which no SaffronRel has been created yet.
SaffronRel	lookupCorrel(String name) Returns the relational expression which populates a correlating variable.
void	mapCorrel(String name, SaffronRel rel) Maps a correlating variable to a SaffronRel.

Methods inherited from class java.lang.Object

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

Field Detail

mapDeferredToCorrel

public final HashMap 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 SaffronRel.

mapCorrelToRel

final HashMap mapCorrelToRel

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

planner

private final VolcanoPlanner planner

nextCorrel

private int nextCorrel

correlPrefix

public static final String correlPrefix

Prefix to the name of correlating variables.

See Also:

Constant Field Values

Constructor Detail

VolcanoQuery

public VolcanoQuery()

VolcanoQuery

public VolcanoQuery(VolcanoPlanner planner)

Method Detail

createCluster

public VolcanoCluster createCluster(Environment env,
                                    SaffronTypeFactory typeFactory)

createCorrel

public String createCorrel()

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

createCorrelUnresolved

public String createCorrelUnresolved(Object deferredLookup)

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

Parameters:

deferredLookup - contains the information required to resolve the variable later

lookupCorrel

public SaffronRel lookupCorrel(String name)

Returns the relational expression which populates a correlating variable.

mapCorrel

public void mapCorrel(String name,
                      SaffronRel rel)

Maps a correlating variable to a SaffronRel.