org.apache.calcite.rex

Class RexSimplify

java.lang.Object

org.apache.calcite.rex.RexSimplify

public class RexSimplify
extends Object

Context required to simplify a row-expression.

Field Summary

Fields

Modifier and Type	Field and Description
RexBuilder	rexBuilder

Constructor Summary

Constructors

Constructor and Description
RexSimplify(RexBuilder rexBuilder, boolean unknownAsFalse, RexExecutor executor) Deprecated.
RexSimplify(RexBuilder rexBuilder, RelOptPredicateList predicates, boolean unknownAsFalse, RexExecutor executor) Deprecated.
RexSimplify(RexBuilder rexBuilder, RelOptPredicateList predicates, RexExecutor executor) Creates a RexSimplify.

Method Summary

Modifier and Type	Method and Description
RexNode	removeNullabilityCast(RexNode e) Removes any casts that change nullability but not type.
RexNode	simplify(RexNode e) Simplifies a boolean expression.
RexNode	simplifyAnd(RexCall e) Deprecated.
RexNode	simplifyAnds(Iterable<? extends RexNode> nodes) Deprecated.
@Nullable RexNode	simplifyFilterPredicates(Iterable<? extends RexNode> predicates) Combines predicates AND, optimizes, and returns null if the result is always false.
RexNode	simplifyOr(RexCall call) Deprecated.
RexNode	simplifyOrs(List<RexNode> terms) Deprecated.
RexNode	simplifyPreservingType(RexNode e) Simplifies a boolean expression, always preserving its type and its nullability.
RexNode	simplifyPreservingType(RexNode e, RexUnknownAs unknownAs, boolean matchNullability)
RexNode	simplifyUnknownAs(RexNode e, RexUnknownAs unknownAs) As simplify(RexNode), but specifying how UNKNOWN values are to be treated.
RexNode	simplifyUnknownAsFalse(RexNode e) As simplify(RexNode), but for a boolean expression for which a result of UNKNOWN will be treated as FALSE.
RexSimplify	withParanoid(boolean paranoid) Returns a RexSimplify the same as this but which verifies that the expression before and after simplification are equivalent.
RexSimplify	withPredicates(RelOptPredicateList predicates) Returns a RexSimplify the same as this but with a specified predicates value.
RexSimplify	withUnknownAsFalse(boolean unknownAsFalse) Deprecated. Use methods with a RexUnknownAs argument, such as simplify(RexNode, RexUnknownAs).

Methods inherited from class java.lang.Object

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

Field Detail

rexBuilder

public final RexBuilder rexBuilder

Constructor Detail

RexSimplify

public RexSimplify(RexBuilder rexBuilder,
                   RelOptPredicateList predicates,
                   RexExecutor executor)

Creates a RexSimplify.

Parameters:

rexBuilder - Rex builder

predicates - Predicates known to hold on input fields

executor - Executor for constant reduction, not null

RexSimplify

@Deprecated
public RexSimplify(RexBuilder rexBuilder,
                               boolean unknownAsFalse,
                               RexExecutor executor)

Deprecated.

RexSimplify

@Deprecated
public RexSimplify(RexBuilder rexBuilder,
                               RelOptPredicateList predicates,
                               boolean unknownAsFalse,
                               RexExecutor executor)

Deprecated.

Method Detail

withUnknownAsFalse

@Deprecated
public RexSimplify withUnknownAsFalse(boolean unknownAsFalse)

Deprecated. Use methods with a RexUnknownAs argument, such as simplify(RexNode, RexUnknownAs).

Returns a RexSimplify the same as this but with a specified defaultUnknownAs value.

withPredicates

public RexSimplify withPredicates(RelOptPredicateList predicates)

Returns a RexSimplify the same as this but with a specified predicates value.

withParanoid

public RexSimplify withParanoid(boolean paranoid)

Returns a RexSimplify the same as this but which verifies that the expression before and after simplification are equivalent.

See Also:

verify(org.apache.calcite.rex.RexNode, org.apache.calcite.rex.RexNode, org.apache.calcite.rex.RexUnknownAs)

simplifyPreservingType

public RexNode simplifyPreservingType(RexNode e)

Simplifies a boolean expression, always preserving its type and its nullability.

This is useful if you are simplifying expressions in a Project.

simplifyPreservingType

public RexNode simplifyPreservingType(RexNode e,
                                      RexUnknownAs unknownAs,
                                      boolean matchNullability)

simplify

public RexNode simplify(RexNode e)

Simplifies a boolean expression.

In particular:

• simplify(x = 1 OR NOT x = 1 OR x IS NULL) returns TRUE
• simplify(x = 1 AND FALSE) returns FALSE

Handles UNKNOWN values using the policy specified when you created this RexSimplify. Unless you used a deprecated constructor, that policy is RexUnknownAs.UNKNOWN.

If the expression is a predicate in a WHERE clause, consider instead using simplifyUnknownAsFalse(RexNode).

Parameters:

e - Expression to simplify

simplifyUnknownAsFalse

public final RexNode simplifyUnknownAsFalse(RexNode e)

As simplify(RexNode), but for a boolean expression for which a result of UNKNOWN will be treated as FALSE.

Use this form for expressions on a WHERE, ON, HAVING or FILTER(WHERE) clause.

This may allow certain additional simplifications. A result of UNKNOWN may yield FALSE, however it may still yield UNKNOWN. (If the simplified expression has type BOOLEAN NOT NULL, then of course it can only return FALSE.)

simplifyUnknownAs

public RexNode simplifyUnknownAs(RexNode e,
                                 RexUnknownAs unknownAs)

As simplify(RexNode), but specifying how UNKNOWN values are to be treated.

If UNKNOWN is treated as FALSE, this may allow certain additional simplifications. A result of UNKNOWN may yield FALSE, however it may still yield UNKNOWN. (If the simplified expression has type BOOLEAN NOT NULL, then of course it can only return FALSE.)

simplifyAnds

@Deprecated
public RexNode simplifyAnds(Iterable<? extends RexNode> nodes)

Deprecated.

Simplifies a conjunction of boolean expressions.

simplifyAnd

@Deprecated
public RexNode simplifyAnd(RexCall e)

Deprecated.

simplifyOr

@Deprecated
public RexNode simplifyOr(RexCall call)

Deprecated.

Simplifies OR(x, x) into x, and similar. The simplified expression returns UNKNOWN values as is (not as FALSE).

simplifyOrs

@Deprecated
public RexNode simplifyOrs(List<RexNode> terms)

Deprecated.

Simplifies a list of terms and combines them into an OR. Modifies the list in place. The simplified expression returns UNKNOWN values as is (not as FALSE).

removeNullabilityCast

public RexNode removeNullabilityCast(RexNode e)

Removes any casts that change nullability but not type.

For example, CAST(1 = 0 AS BOOLEAN) becomes 1 = 0.

simplifyFilterPredicates

public @Nullable RexNode simplifyFilterPredicates(Iterable<? extends RexNode> predicates)

Combines predicates AND, optimizes, and returns null if the result is always false.

The expression is simplified on the assumption that an UNKNOWN value is always treated as FALSE. Therefore the simplified expression may sometimes evaluate to FALSE where the original expression would evaluate to UNKNOWN.

Parameters:

predicates - Filter condition predicates

Returns:

simplified conjunction of predicates for the filter, null if always false