org.apache.calcite.plan

Class Strong

java.lang.Object

org.apache.calcite.plan.Strong

public class Strong
extends Object

Utilities for strong predicates.

A predicate is strong (or null-rejecting) if it is UNKNOWN if any of its inputs is UNKNOWN.

By the way, UNKNOWN is just the boolean form of NULL.

Examples:

• UNKNOWN is strong in [] (definitely null)
• c = 1 is strong in [c] (definitely null if and only if c is null)
• c IS NULL is not strong (always returns TRUE or FALSE, never null)
• p1 AND p2 is strong in [p1, p2] (definitely null if either p1 is null or p2 is null)
• p1 OR p2 is strong if p1 and p2 are strong
• c1 = 1 OR c2 IS NULL is strong in [c1] (definitely null if c1 is null)

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Strong.Policy How whether an operator's operands are null affects whether a call to that operator evaluates to null.

Constructor Summary

Constructors

Constructor and Description
Strong()

Method Summary

Modifier and Type	Method and Description
static boolean	allStrong(List<RexNode> operands) Returns whether all expressions in a list are strong.
boolean	isNotTrue(RexNode node) Returns whether an expression is definitely not true.
static boolean	isNotTrue(RexNode node, ImmutableBitSet nullColumns) Returns whether the analyzed expression will definitely not return true (equivalently, will definitely not return null or false) if all of a given set of input columns are null.
boolean	isNull(RexInputRef ref) Returns whether a given input is definitely null.
boolean	isNull(RexNode node) Returns whether an expression is definitely null.
static boolean	isNull(RexNode node, ImmutableBitSet nullColumns) Returns whether the analyzed expression will definitely return null if all of a given set of input columns are null.
static boolean	isStrong(RexNode e) Returns whether a given expression is strong.
static Strong	of(ImmutableBitSet nullColumns) Returns a checker that consults a bit set to find out whether particular inputs may be null.
static Strong.Policy	policy(RexNode rexNode) Returns how to deduce whether a particular RexNode expression is null, given whether its arguments are null.
static Strong.Policy	policy(SqlKind kind) Deprecated. Use policy(RexNode) or policy(SqlOperator)
static Strong.Policy	policy(SqlOperator operator) Returns how to deduce whether a particular SqlOperator expression is null, given whether its arguments are null.

Methods inherited from class java.lang.Object

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

Constructor Detail

Strong

public Strong()

Method Detail

of

public static Strong of(ImmutableBitSet nullColumns)

Returns a checker that consults a bit set to find out whether particular inputs may be null.

isNull

public static boolean isNull(RexNode node,
                             ImmutableBitSet nullColumns)

Returns whether the analyzed expression will definitely return null if all of a given set of input columns are null.

isNotTrue

public static boolean isNotTrue(RexNode node,
                                ImmutableBitSet nullColumns)

Returns whether the analyzed expression will definitely not return true (equivalently, will definitely not return null or false) if all of a given set of input columns are null.

policy

@Deprecated
public static Strong.Policy policy(SqlKind kind)

Deprecated. Use policy(RexNode) or policy(SqlOperator)

Returns how to deduce whether a particular kind of expression is null, given whether its arguments are null.

policy

public static Strong.Policy policy(RexNode rexNode)

Returns how to deduce whether a particular RexNode expression is null, given whether its arguments are null.

policy

public static Strong.Policy policy(SqlOperator operator)

Returns how to deduce whether a particular SqlOperator expression is null, given whether its arguments are null.

isStrong

public static boolean isStrong(RexNode e)

Returns whether a given expression is strong.

Examples:

• Returns true for c = 1 since it returns null if and only if c is null
• Returns false for c IS NULL since it always returns TRUE or FALSE

Parameters:

e - Expression

Returns:

true if the expression is strong, false otherwise

allStrong

public static boolean allStrong(List<RexNode> operands)

Returns whether all expressions in a list are strong.

isNotTrue

public boolean isNotTrue(RexNode node)

Returns whether an expression is definitely not true.

isNull

public boolean isNull(RexNode node)

Returns whether an expression is definitely null.

The answer is based on calls to isNull(org.apache.calcite.rex.RexNode, org.apache.calcite.util.ImmutableBitSet) for its constituent expressions, and you may override methods to test hypotheses such as "if x is null, is x + y null?

isNull

public boolean isNull(RexInputRef ref)

Returns whether a given input is definitely null.