org.apache.calcite.rel.rules

Class SubQueryRemoveRule

java.lang.Object

org.apache.calcite.plan.RelOptRule

org.apache.calcite.rel.rules.SubQueryRemoveRule

Direct Known Subclasses:

SubQueryRemoveRule.SubQueryFilterRemoveRule, SubQueryRemoveRule.SubQueryJoinRemoveRule, SubQueryRemoveRule.SubQueryProjectRemoveRule

public abstract class SubQueryRemoveRule
extends RelOptRule

Transform that converts IN, EXISTS and scalar sub-queries into joins.

Sub-queries are represented by RexSubQuery expressions.

A sub-query may or may not be correlated. If a sub-query is correlated, the wrapped RelNode will contain a RexCorrelVariable before the rewrite, and the product of the rewrite will be a Correlate. The Correlate can be removed using RelDecorrelator.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private static class	SubQueryRemoveRule.ReplaceSubQueryShuttle Shuttle that replaces occurrences of a given RexSubQuery with a replacement expression.
static class	SubQueryRemoveRule.SubQueryFilterRemoveRule Rule that converts a sub-queries from filter expressions into Correlate instances.
static class	SubQueryRemoveRule.SubQueryJoinRemoveRule Rule that converts sub-queries from join expressions into Correlate instances.
static class	SubQueryRemoveRule.SubQueryProjectRemoveRule Rule that converts sub-queries from project expressions into Correlate instances.

Field Summary

Fields

Modifier and Type	Field and Description
static SubQueryRemoveRule	FILTER
static SubQueryRemoveRule	JOIN
static SubQueryRemoveRule	PROJECT

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

description, operands, relBuilderFactory

Constructor Summary

Constructors

Constructor and Description
SubQueryRemoveRule(RelOptRuleOperand operand, RelBuilderFactory relBuilderFactory, String description) Creates a SubQueryRemoveRule.

Method Summary

Modifier and Type	Method and Description
protected RexNode	apply(RexSubQuery e, Set<CorrelationId> variablesSet, RelOptUtil.Logic logic, RelBuilder builder, int inputCount, int offset)
private RexInputRef	field(RelBuilder builder, int inputCount, int offset) Returns a reference to a particular field, by offset, across several inputs on a RelBuilder's stack.
private static List<RexNode>	fields(RelBuilder builder, int fieldCount) Returns a list of expressions that project the first fieldCount fields of the top input on a RelBuilder's stack.
private RexNode	rewriteExists(RexSubQuery e, Set<CorrelationId> variablesSet, RelOptUtil.Logic logic, RelBuilder builder) Rewrites an EXISTS RexSubQuery into a Join.
private RexNode	rewriteIn(RexSubQuery e, Set<CorrelationId> variablesSet, RelOptUtil.Logic logic, RelBuilder builder, int offset) Rewrites an IN RexSubQuery into a Join.
private RexNode	rewriteScalarQuery(RexSubQuery e, Set<CorrelationId> variablesSet, RelBuilder builder, int inputCount, int offset) Rewrites a scalar sub-query into an Aggregate.
private RexNode	rewriteSome(RexSubQuery e, RelBuilder builder) Rewrites a SOME sub-query into a Join.

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

any, convert, convert, convertList, convertOperand, convertOperand, equals, equals, getOperand, getOperands, getOutConvention, getOutTrait, hashCode, matches, none, onMatch, 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

Field Detail

PROJECT

public static final SubQueryRemoveRule PROJECT

FILTER

public static final SubQueryRemoveRule FILTER

JOIN

public static final SubQueryRemoveRule JOIN

Constructor Detail

SubQueryRemoveRule

public SubQueryRemoveRule(RelOptRuleOperand operand,
                          RelBuilderFactory relBuilderFactory,
                          String description)

Creates a SubQueryRemoveRule.

Parameters:

operand - root operand, must not be null

description - Description, or null to guess description

relBuilderFactory - Builder for relational expressions

Method Detail

apply

protected RexNode apply(RexSubQuery e,
                        Set<CorrelationId> variablesSet,
                        RelOptUtil.Logic logic,
                        RelBuilder builder,
                        int inputCount,
                        int offset)

rewriteScalarQuery

private RexNode rewriteScalarQuery(RexSubQuery e,
                                   Set<CorrelationId> variablesSet,
                                   RelBuilder builder,
                                   int inputCount,
                                   int offset)

Rewrites a scalar sub-query into an Aggregate.

Parameters:

e - IN sub-query to rewrite

variablesSet - A set of variables used by a relational expression of the specified RexSubQuery

builder - Builder

offset - Offset to shift RexInputRef

Returns:

Expression that may be used to replace the RexSubQuery

rewriteSome

private RexNode rewriteSome(RexSubQuery e,
                            RelBuilder builder)

Rewrites a SOME sub-query into a Join.

Parameters:

e - SOME sub-query to rewrite

builder - Builder

Returns:

Expression that may be used to replace the RexSubQuery

rewriteExists

private RexNode rewriteExists(RexSubQuery e,
                              Set<CorrelationId> variablesSet,
                              RelOptUtil.Logic logic,
                              RelBuilder builder)

Rewrites an EXISTS RexSubQuery into a Join.

Parameters:

e - EXISTS sub-query to rewrite

variablesSet - A set of variables used by a relational expression of the specified RexSubQuery

logic - Logic for evaluating

builder - Builder

Returns:

Expression that may be used to replace the RexSubQuery

rewriteIn

private RexNode rewriteIn(RexSubQuery e,
                          Set<CorrelationId> variablesSet,
                          RelOptUtil.Logic logic,
                          RelBuilder builder,
                          int offset)

Rewrites an IN RexSubQuery into a Join.

Parameters:

e - IN sub-query to rewrite

variablesSet - A set of variables used by a relational expression of the specified RexSubQuery

logic - Logic for evaluating

builder - Builder

offset - Offset to shift RexInputRef

Returns:

Expression that may be used to replace the RexSubQuery

field

private RexInputRef field(RelBuilder builder,
                          int inputCount,
                          int offset)

Returns a reference to a particular field, by offset, across several inputs on a RelBuilder's stack.

fields

private static List<RexNode> fields(RelBuilder builder,
                                    int fieldCount)

Returns a list of expressions that project the first fieldCount fields of the top input on a RelBuilder's stack.