com.bigdata.bop.join

Enum JoinTypeEnum

java.lang.Object

java.lang.Enum<JoinTypeEnum>

com.bigdata.bop.join.JoinTypeEnum

All Implemented Interfaces:

Serializable, Comparable<JoinTypeEnum>

public enum JoinTypeEnum
extends Enum<JoinTypeEnum>

A type safe enumeration of the different flavors of hash index "joins".

Version:

$Id$

Author:

Bryan Thompson

Enum Constant Summary

Enum Constants

Enum Constant and Description
Exists A join where the left solution is output iff there exists at least one right solution which joins with that left solution.
Filter A distinct filter (not a join).
Normal A normal join.
NotExists A join where the left solution is output iff there is no right solution which joins with that left solution.
Optional An optional join.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	isFilter() Return true iff this is a DISTINCT SOLUTIONS filter.
boolean	isNormal() Return true iff this is a Normal join.
boolean	isOptional() Return true iff this is a JOIN with OPTIONAL semantics.
static JoinTypeEnum	valueOf(String name) Returns the enum constant of this type with the specified name.
static JoinTypeEnum[]	values() Returns an array containing the constants of this enum type, in the order they are declared.

Methods inherited from class java.lang.Enum

clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Enum Constant Detail

Normal

public static final JoinTypeEnum Normal

A normal join. The output is the combination of the left and right hand solutions. Only solutions which join are output.

Optional

public static final JoinTypeEnum Optional

An optional join. The output is the combination of the left and right hand solutions. Solutions which join are output, plus any left solutions which did not join. Constraints on the join ARE NOT applied to the "optional" path.

Exists

public static final JoinTypeEnum Exists

A join where the left solution is output iff there exists at least one right solution which joins with that left solution. For each left solution, that solution is output either zero or one times. In order to enforce this cardinality constraint, the hash join logic winds up populating the "join set" and then outputs the join set once all solutions which join have been identified.

NotExists

public static final JoinTypeEnum NotExists

A join where the left solution is output iff there is no right solution which joins with that left solution. This basically an optional join where the solutions which join are not output.

Note: This is also used for "MINUS" since the only difference between "NotExists" and "MINUS" deals with the scope of the variables.

Filter

public static final JoinTypeEnum Filter

A distinct filter (not a join). Only the distinct left solutions are output. Various annotations pertaining to JOIN processing are ignored when the hash index is used as a DISTINCT filter.

Method Detail

values

public static JoinTypeEnum[] values()

Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:

for (JoinTypeEnum c : JoinTypeEnum.values())
    System.out.println(c);

Returns:

an array containing the constants of this enum type, in the order they are declared

valueOf

public static JoinTypeEnum valueOf(String name)

Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)

Parameters:

name - the name of the enum constant to be returned.

Returns:

the enum constant with the specified name

Throws:

IllegalArgumentException - if this enum type has no constant with the specified name

NullPointerException - if the argument is null

isFilter

public boolean isFilter()

Return true iff this is a DISTINCT SOLUTIONS filter.

See Also:

Filter

isOptional

public boolean isOptional()

Return true iff this is a JOIN with OPTIONAL semantics.

See Also:

Optional, IPredicate.Annotations#OPTIONAL

isNormal

public boolean isNormal()

Return true iff this is a Normal join.