Package org.apache.calcite.rel.rules

Class FilterFlattenCorrelatedConditionRule

java.lang.Object

org.apache.calcite.plan.RelOptRule

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

org.apache.calcite.rel.rules.FilterFlattenCorrelatedConditionRule

@API(since="1.27",
     status=EXPERIMENTAL)
@Enclosing
public final class FilterFlattenCorrelatedConditionRule
extends RelRule<FilterFlattenCorrelatedConditionRule.Config>

Planner rule that matches a Filter expression with correlated variables, and rewrites the condition in a simpler form that is more convenient for the decorrelation logic.

Uncorrelated calls below a comparison operator are turned into input references by extracting the computation in a Project expression. An additional projection may be added on top of the new filter to retain expression equivalence.

Sub-plan before

 LogicalProject($f0=[true])
   LogicalFilter(condition=[=($cor0.DEPTNO, +($7, 30))])
     LogicalTableScan(table=[[CATALOG, SALES, EMP]])
 

Sub-plan after

 LogicalProject($f0=[true])
   LogicalProject(EMPNO=[$0], ENAME=[$1], JOB=[$2],..., COMM=[$6], DEPTNO=[$7], SLACKER=[$8])
     LogicalFilter(condition=[=($cor0.DEPTNO, $9)])
       LogicalProject(EMPNO=[$0], ENAME=[$1], JOB=[$2],..., SLACKER=[$8], $f9=[+($7, 30)])
         LogicalTableScan(table=[[CATALOG, SALES, EMP]])
 

The rule should be used in conjunction with other rules and transformations to have a positive impact on the plan. At the moment it is tightly connected with the decorrelation logic and may not be useful in a broader context. Projects may implement decorrelation differently so they may choose to use this rule or not.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	FilterFlattenCorrelatedConditionRule.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

Constructor	Description
FilterFlattenCorrelatedConditionRule(FilterFlattenCorrelatedConditionRule.Config config)

Method Summary

Modifier and Type	Method	Description
boolean	matches(RelOptRuleCall call)	Returns whether this rule could possibly match the given operands.
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, getOutConvention, getOutTrait, hashCode, 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

FilterFlattenCorrelatedConditionRule

public FilterFlattenCorrelatedConditionRule(FilterFlattenCorrelatedConditionRule.Config config)

Method Details

matches

public boolean matches(RelOptRuleCall call)

Description copied from class: RelOptRule

Returns whether this rule could possibly match the given operands.

This method is an opportunity to apply side-conditions to a rule. The RelOptPlanner calls this method after matching all operands of the rule, and before calling RelOptRule.onMatch(RelOptRuleCall).

In implementations of RelOptPlanner which may queue up a matched RelOptRuleCall for a long time before calling RelOptRule.onMatch(RelOptRuleCall), this method is beneficial because it allows the planner to discard rules earlier in the process.

The default implementation of this method returns true. It is acceptable for any implementation of this method to give a false positives, that is, to say that the rule matches the operands but have RelOptRule.onMatch(RelOptRuleCall) subsequently not generate any successors.

The following script is useful to identify rules which commonly produce no successors. You should override this method for these rules:

awk '
 /Apply rule/ {rule=$4; ruleCount[rule]++;}
 /generated 0 successors/ {ruleMiss[rule]++;}
 END {
   printf "%-30s %s %s\n", "Rule", "Fire", "Miss";
   for (i in ruleCount) {
     printf "%-30s %5d %5d\n", i, ruleCount[i], ruleMiss[i];
   }
 } ' FarragoTrace.log

Overrides:

matches in class RelOptRule

Parameters:

call - Rule call which has been determined to match all operands of this rule

Returns:

whether this RelOptRule matches a given RelOptRuleCall

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)