Module com.darkcollective.relix.cost

Package com.darkcollective.relix.cost

Enum Class Boundedness

java.lang.Object

java.lang.Enum<Boundedness>

com.darkcollective.relix.cost.Boundedness

All Implemented Interfaces:

Serializable, Comparable<Boundedness>, Constable

public enum Boundedness
extends Enum<Boundedness>

Whether a relation is guaranteed finite — a logical property propagated bottom-up over a RelNode tree.

The three values form a lattice ordered by "how unbounded":

 BOUNDED  <  UNKNOWN  <  UNBOUNDED 

• BOUNDED — provably finite (files, database tables, inline and catalog relations, finite generators).
• UNKNOWN — finiteness cannot be proven either way. The safety check does not reject UNKNOWN — only what is provably UNBOUNDED.
• UNBOUNDED — provably infinite (an unbounded generator such as Naturals or Primes, or a streaming source). No operator or default ever produces UNBOUNDED; it originates only at a leaf and propagates upward (the "contagious-only" invariant), so a tree whose leaves are all bounded is itself provably bounded.

This boundedness property is distinct from cardinality: an honestly unknown row count (a JDBC table without statistics) is still BOUNDED, not UNKNOWN.

Nested Class Summary

Nested classes/interfaces inherited from class java.lang.Enum

Enum.EnumDesc<E extends Enum<E>>

Enum Constant Summary

Enum Constants

Enum Constant	Description
BOUNDED	Provably finite.
UNBOUNDED	Provably infinite.
UNKNOWN	Finiteness cannot be proven; conservatively allowed (not rejected).

Method Summary

Modifier and Type	Method	Description
Boundedness	lub(Boundedness other)	The least upper bound of this and other — the boundedness of an operator combining inputs of these boundednesses.
static Boundedness	valueOf(String name)	Returns the enum constant of this class with the specified name.
static Boundedness[]	values()	Returns an array containing the constants of this enum class, in the order they are declared.

Methods inherited from class java.lang.Enum

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

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Enum Constant Details

BOUNDED

public static final Boundedness BOUNDED

Provably finite.

UNKNOWN

public static final Boundedness UNKNOWN

Finiteness cannot be proven; conservatively allowed (not rejected).

UNBOUNDED

public static final Boundedness UNBOUNDED

Provably infinite.

Method Details

values

public static Boundedness[] values()

Returns an array containing the constants of this enum class, in the order they are declared.

Returns:

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

valueOf

public static Boundedness valueOf(String name)

Returns the enum constant of this class with the specified name. The string must match exactly an identifier used to declare an enum constant in this class. (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 class has no constant with the specified name

NullPointerException - if the argument is null

lub

public Boundedness lub(Boundedness other)

The least upper bound of this and other — the boundedness of an operator combining inputs of these boundednesses. Because the lattice is a total order, this is the more-unbounded of the two (so any unbounded input makes the combination unbounded; the contagious-only invariant).

Parameters:

other - the other boundedness; must not be null

Returns:

the more-unbounded of the two