Package org.apache.calcite.rel.rules

Class ReduceDecimalsRule

java.lang.Object

org.apache.calcite.plan.RelOptRule

org.apache.calcite.plan.RelRule<ReduceDecimalsRule.Config>

org.apache.calcite.rel.rules.ReduceDecimalsRule

All Implemented Interfaces:

TransformationRule

@Enclosing
public class ReduceDecimalsRule
extends RelRule<ReduceDecimalsRule.Config>
implements TransformationRule

Rule that reduces decimal operations (such as casts or arithmetic) into operations involving more primitive types (such as longs and doubles). The rule allows Calcite implementations to deal with decimals in a consistent manner, while saving the effort of implementing them.

The rule can be applied to a LogicalCalc with a program for which RexUtil.requiresDecimalExpansion(org.apache.calcite.rex.RexNode, boolean) returns true. The rule relies on a RexShuttle to walk over relational expressions and replace them.

While decimals are generally not implemented by the Calcite runtime, the rule is optionally applied, in order to support the situation in which we would like to push down decimal operations to an external database.

See Also:

• CoreRules.CALC_REDUCE_DECIMALS

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	ReduceDecimalsRule.Config	Rule configuration.
static class	ReduceDecimalsRule.DecimalShuttle	A shuttle which converts decimal expressions to expressions based on longs.
static class	ReduceDecimalsRule.RexExpander	Rewrites a decimal expression for a specific set of SqlOperator's.

Nested classes/interfaces inherited from class org.apache.calcite.plan.RelRule

RelRule.Done, RelRule.MatchHandler<R extends RelOptRule>, RelRule.OperandBuilder, RelRule.OperandDetailBuilder<R extends RelNode>, RelRule.OperandTransform

Nested classes/interfaces inherited from class org.apache.calcite.plan.RelOptRule

RelOptRule.ConverterRelOptRuleOperand

Field Summary

Fields inherited from class org.apache.calcite.plan.RelRule

config

Fields inherited from class org.apache.calcite.plan.RelOptRule

description, operands, relBuilderFactory

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	ReduceDecimalsRule(ReduceDecimalsRule.Config config)	Creates a ReduceDecimalsRule.
	ReduceDecimalsRule(RelBuilderFactory relBuilderFactory)	Deprecated.

Method Summary

Modifier and Type	Method	Description
@Nullable Convention	getOutConvention()	Returns the convention of the result of firing this rule, null if not known.
void	onMatch(RelOptRuleCall call)	Receives notification about a rule match.

Methods inherited from class org.apache.calcite.plan.RelOptRule

any, convert, convert, convert, convert, convertList, convertOperand, convertOperand, equals, equals, getOperand, getOperands, getOutTrait, hashCode, matches, none, operand, operand, operand, operand, operand, operandJ, operandJ, some, toString, unordered

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Details

ReduceDecimalsRule

protected ReduceDecimalsRule(ReduceDecimalsRule.Config config)

Creates a ReduceDecimalsRule.

ReduceDecimalsRule

@Deprecated
public ReduceDecimalsRule(RelBuilderFactory relBuilderFactory)

Deprecated.

Method Details

getOutConvention

public @Nullable Convention getOutConvention()

Description copied from class: RelOptRule

Returns the convention of the result of firing this rule, null if not known.

Overrides:

getOutConvention in class RelOptRule

Returns:

Convention of the result of firing this rule, null if not known

onMatch

public void onMatch(RelOptRuleCall call)

Description copied from class: RelOptRule

Receives notification about a rule match. At the time that this method is called, call.rels holds the set of relational expressions which match the operands to the rule; call.rels[0] is the root expression.

Typically a rule would check that the nodes are valid matches, creates a new expression, then calls back RelOptRuleCall.transformTo(org.apache.calcite.rel.RelNode, java.util.Map<org.apache.calcite.rel.RelNode, org.apache.calcite.rel.RelNode>, org.apache.calcite.plan.RelHintsPropagator) to register the expression.

Specified by:

onMatch in class RelOptRule

Parameters:

call - Rule call

See Also:

• RelOptRule.matches(RelOptRuleCall)