org.apache.calcite.rel.rules

Class AggregateExpandWithinDistinctRule

java.lang.Object

org.apache.calcite.plan.RelOptRule

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

org.apache.calcite.rel.rules.AggregateExpandWithinDistinctRule

@Value.Enclosing
public class AggregateExpandWithinDistinctRule
extends RelRule<AggregateExpandWithinDistinctRule.Config>

Planner rule that rewrites an Aggregate that contains WITHIN DISTINCT aggregate functions.

For example,

SELECT o.paymentType,
     COUNT(*) as "count",
     COUNT(*) WITHIN DISTINCT (o.orderId) AS orderCount,
     SUM(o.shipping) WITHIN DISTINCT (o.orderId) as sumShipping,
     SUM(i.units) as sumUnits
   FROM Orders AS o
   JOIN OrderItems AS i USING (orderId)
   GROUP BY o.paymentType

becomes

     SELECT paymentType,
       COUNT(*) as "count",
       COUNT(*) FILTER (WHERE g = 0) AS orderCount,
       SUM(minShipping) FILTER (WHERE g = 0) AS sumShipping,
       SUM(sumUnits) FILTER (WHERE g = 1) as sumUnits
    FROM (
      SELECT o.paymentType,
        GROUPING(o.orderId) AS g,
        SUM(o.shipping) AS sumShipping,
        MIN(o.shipping) AS minShipping,
        SUM(i.units) AS sumUnits
        FROM Orders AS o
        JOIN OrderItems ON o.orderId = i.orderId
        GROUP BY GROUPING SETS ((o.paymentType), (o.paymentType, o.orderId)))
     GROUP BY o.paymentType

By the way, note that COUNT(*) WITHIN DISTINCT (o.orderId) is identical to COUNT(DISTINCT o.orderId). WITHIN DISTINCT is a generalization of aggregate(DISTINCT). So, it is perhaps not surprising that the rewrite to GROUPING SETS is similar.

If there are multiple arguments (e.g. SUM(a) WITHIN DISTINCT (x), SUM(a) WITHIN DISTINCT (y)) the rule creates separate GROUPING SETs.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	AggregateExpandWithinDistinctRule.Config Rule configuration.

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 and Description
protected	AggregateExpandWithinDistinctRule(AggregateExpandWithinDistinctRule.Config config) Creates an AggregateExpandWithinDistinctRule.

Method Summary

Modifier and Type	Method and Description
void	onMatch(RelOptRuleCall call) Receives notification about a rule match.

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

any, convert, convert, convertList, convertOperand, convertOperand, equals, equals, getOperand, getOperands, getOutConvention, 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 Detail

AggregateExpandWithinDistinctRule

protected AggregateExpandWithinDistinctRule(AggregateExpandWithinDistinctRule.Config config)

Creates an AggregateExpandWithinDistinctRule.

Method Detail

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)