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.

Field Summary

Fields

Modifier and Type	Field and Description
private static Map<SqlKind,Strong.Policy>	MAP

Constructor Summary

Constructors

Constructor and Description
Strong()

Method Summary

Modifier and Type	Method and Description
private boolean	allNull(List<RexNode> operands) Returns whether all expressions in a list are definitely null.
private boolean	anyNull(List<RexNode> operands) Returns whether any expressions in a list are definitely null.
private static Map<SqlKind,Strong.Policy>	createPolicyMap()
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 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(SqlKind kind) Returns how to deduce whether a particular kind of 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

Field Detail

MAP

private static final Map<SqlKind,Strong.Policy> MAP

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

public static Strong.Policy policy(SqlKind kind)

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

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.

allNull

private boolean allNull(List<RexNode> operands)

Returns whether all expressions in a list are definitely null.

anyNull

private boolean anyNull(List<RexNode> operands)

Returns whether any expressions in a list are definitely null.

createPolicyMap

private static Map<SqlKind,Strong.Policy> createPolicyMap()