org.apache.calcite.rel.rules

Class SortUnionTransposeRule

java.lang.Object

org.apache.calcite.plan.RelOptRule

org.apache.calcite.rel.rules.SortUnionTransposeRule

public class SortUnionTransposeRule
extends RelOptRule

Planner rule that pushes a Sort past a Union.

Field Summary

Fields

Modifier and Type	Field and Description
static SortUnionTransposeRule	INSTANCE Rule instance for Union implementation that does not preserve the ordering of its inputs.
static SortUnionTransposeRule	MATCH_NULL_FETCH Rule instance for Union implementation that preserves the ordering of its inputs.
private boolean	matchNullFetch Whether to match a Sort whose Sort.fetch is null.

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

description, operands, relBuilderFactory

Constructor Summary

Constructors

Modifier	Constructor and Description
private	SortUnionTransposeRule(boolean matchNullFetch)
	SortUnionTransposeRule(Class<? extends Sort> sortClass, Class<? extends Union> unionClass, boolean matchNullFetch, RelBuilderFactory relBuilderFactory, String description) Creates a SortUnionTransposeRule.

Method Summary

Modifier and Type	Method and 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, convertList, convertOperand, equals, equals, getOperand, getOperands, getOutConvention, getOutTrait, hashCode, none, operand, operand, operand, operand, operand, some, toString, unordered

Methods inherited from class java.lang.Object

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

Field Detail

INSTANCE

public static final SortUnionTransposeRule INSTANCE

Rule instance for Union implementation that does not preserve the ordering of its inputs. Thus, it makes no sense to match this rule if the Sort does not have a limit, i.e., Sort.fetch is null.

MATCH_NULL_FETCH

public static final SortUnionTransposeRule MATCH_NULL_FETCH

Rule instance for Union implementation that preserves the ordering of its inputs. It is still worth applying this rule even if the Sort does not have a limit, for the merge of already sorted inputs that the Union can do is usually cheap.

matchNullFetch

private final boolean matchNullFetch

Whether to match a Sort whose Sort.fetch is null. Generally this only makes sense if the Union preserves order (and merges).

Constructor Detail

SortUnionTransposeRule

private SortUnionTransposeRule(boolean matchNullFetch)

SortUnionTransposeRule

public SortUnionTransposeRule(Class<? extends Sort> sortClass,
                              Class<? extends Union> unionClass,
                              boolean matchNullFetch,
                              RelBuilderFactory relBuilderFactory,
                              String description)

Creates a SortUnionTransposeRule.

Method Detail

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>) to register the expression.

Specified by:

onMatch in class RelOptRule

Parameters:

call - Rule call

See Also:

RelOptRule.matches(RelOptRuleCall)