saffron.opt
Class Query

java.lang.Object
  |
  +--saffron.opt.Query

public class Query

extends Object

A Query represents a set of Rels which come from the same select statement.

Field Summary

(package private) HashMap	mapCorelToRel Maps name of correlating variable (e.g.
HashMap	mapDeferredToCorel Maps a from-list expression to the name of the correlating variable which references it.
private int	nextCorel
private VolcanoPlanner	planner

Constructor Summary

Query()

Method Summary

Cluster	createCluster(Environment env, Expression exp, TypeFactory typeFactory)
String	createCorel() Constructs a new name for a correlating variable.
String	createCorelUnresolved(Object deferredLookup) Creates a name for a correlating variable for which no Rel has been created yet.
Rel	lookupCorel(String name) Returns the relational expression which populates a correlating variable.
void	mapCorel(String name, Rel rel) Maps a correlating variable to a Rel.

Methods inherited from class java.lang.Object

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

Field Detail

nextCorel

private int nextCorel

mapCorelToRel

final HashMap mapCorelToRel

Maps name of correlating variable (e.g. "$Corel3") to the Rel which implements it.

mapDeferredToCorel

public final HashMap mapDeferredToCorel

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 Rel.

planner

private final VolcanoPlanner planner

Constructor Detail

Query

public Query()

Method Detail

createCorel

public String createCorel()

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

mapCorel

public void mapCorel(String name,
                     Rel rel)

Maps a correlating variable to a Rel.

createCorelUnresolved

public String createCorelUnresolved(Object deferredLookup)

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

Parameters:

deferredLookup - contains the information required to resolve the variable later

lookupCorel

public Rel lookupCorel(String name)

Returns the relational expression which populates a correlating variable.

createCluster

public Cluster createCluster(Environment env,
                             Expression exp,
                             TypeFactory typeFactory)