com.apple.foundationdb.record.query.plan.temp.expressions

Class LogicalDistinctExpression

java.lang.Object

com.apple.foundationdb.record.query.plan.temp.expressions.LogicalDistinctExpression

All Implemented Interfaces:

Bindable, RelationalExpressionWithChildren, RelationalPlannerExpression, PlannerExpression

@API(value=EXPERIMENTAL)
public class LogicalDistinctExpression
extends Object
implements RelationalExpressionWithChildren

A relational planner expression representing a stream of unique records. This expression has a single child which is also a RelationalPlannerExpression. This expression represents this underlying expression with its result set de-duplicated.

See Also:

for the fallback implementation

Constructor Summary

Constructors

Constructor and Description
LogicalDistinctExpression(ExpressionRef<RelationalPlannerExpression> inner)
LogicalDistinctExpression(RelationalPlannerExpression inner)

Method Summary

Modifier and Type	Method and Description
ExpressionRef<RelationalPlannerExpression>	asNestedWith(NestedContext nestedContext, ExpressionRef<RelationalPlannerExpression> thisRef) Produce an exactly equivalent version of the PlannerExpression tree rooted at this RelationalPlannerExpression as if all operations were nested inside the given NestedContext.
ExpressionRef<RelationalPlannerExpression>	asUnnestedWith(NestedContext nestedContext, ExpressionRef<RelationalPlannerExpression> thisRef) Produce an exactly equivalent version of the PlannerExpression tree rooted at this RelationalPlannerExpression with all operations placed inside the field given by the NestedContext.
boolean	equals(Object o)
boolean	equalsWithoutChildren(PlannerExpression otherExpression)
Iterator<? extends ExpressionRef<? extends PlannerExpression>>	getPlannerExpressionChildren() Return an iterator of references to the children of this planner expression.
int	getRelationalChildCount()
int	hashCode()

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.apple.foundationdb.record.query.plan.temp.expressions.RelationalPlannerExpression

fromRecordQuery

Methods inherited from interface com.apple.foundationdb.record.query.plan.temp.PlannerExpression

acceptPropertyVisitor, bindTo

Constructor Detail

LogicalDistinctExpression

public LogicalDistinctExpression(@Nonnull
                                 RelationalPlannerExpression inner)

LogicalDistinctExpression

public LogicalDistinctExpression(@Nonnull
                                 ExpressionRef<RelationalPlannerExpression> inner)

Method Detail

getRelationalChildCount

public int getRelationalChildCount()

Specified by:

getRelationalChildCount in interface RelationalExpressionWithChildren

getPlannerExpressionChildren

@Nonnull
public Iterator<? extends ExpressionRef<? extends PlannerExpression>> getPlannerExpressionChildren()

Description copied from interface: PlannerExpression

Return an iterator of references to the children of this planner expression. The iterators returned by different calls are guaranteed to be independent (i.e., advancing one will not advance another). However, they might point to the same object, as when Collections.emptyIterator() is returned. The returned iterator should be treated as an immutable object and may throw an exception if Iterator.remove() is called. The iterator must return its elements in a consistent order.

Specified by:

getPlannerExpressionChildren in interface PlannerExpression

Returns:

an iterator of references to the children of this planner expression

asNestedWith

@Nullable
public ExpressionRef<RelationalPlannerExpression> asNestedWith(@Nonnull
                                                                         NestedContext nestedContext,
                                                                         @Nonnull
                                                                         ExpressionRef<RelationalPlannerExpression> thisRef)

Description copied from interface: RelationalPlannerExpression

Produce an exactly equivalent version of the PlannerExpression tree rooted at this RelationalPlannerExpression as if all operations were nested inside the given NestedContext. That is, transform all predicates, index scans, and other operations to the form that they would have if they were nested within the field given by the parent field of the given nested context. If it is not possible to produce such an expression, return null.

With RelationalPlannerExpression.asUnnestedWith(NestedContext, ExpressionRef), this method should obey the contract that, for any expression and nestedContext, expression.asNestedWith(nestedContext, ref).asUnnestedWith(nestedContext, ref) is either equal to expression (according to the equals() comparison) or null.

For example, if this expression is a filter on the predicate field("a").matches(field("b).equals(3)), with an inner FullUnorderedScanExpression, and the nestedContext is built around field("a"), then this method would return a reference containing a logical filter on the predicate field("b").equals(3) with an inner FullUnorderedScanExpression.

The thisRef parameter has two uses. For some implementations of asNestedWith(), the expression does not need to be changed, and so it is more efficient to return the containing reference than to build a new one. Additionally, it is used to generate a reference of the appropriate type using the ExpressionRef.getNewRefWith(PlannerExpression).

Specified by:

asNestedWith in interface RelationalPlannerExpression

Parameters:

nestedContext - a context describing the field to use for nesting

thisRef - the reference that contains this relational planner expression

Returns:

a nested version of this expression with respect to the given context, or null if no such expression exists

asUnnestedWith

@Nullable
public ExpressionRef<RelationalPlannerExpression> asUnnestedWith(@Nonnull
                                                                           NestedContext nestedContext,
                                                                           @Nonnull
                                                                           ExpressionRef<RelationalPlannerExpression> thisRef)

Description copied from interface: RelationalPlannerExpression

Produce an exactly equivalent version of the PlannerExpression tree rooted at this RelationalPlannerExpression with all operations placed inside the field given by the NestedContext. That is, put all predicates, index scans, and other operations within the given nested field. If it is not possible to produce such an expression, return null.

With RelationalPlannerExpression.asNestedWith(NestedContext, ExpressionRef), this method should obey the contract that, for any expression and nestedContext, expression.asNestedWith(nestedContext, ref).asUnnestedWith(nestedContext, ref) is either equal to expression (according to the equals() comparison) or null.

For example, if this expression is a logical filter on the predicate field("b).equals(3), with an inner FullUnorderedScanExpression, and the nestedContext is built around field("a"), then this method would return a reference containing a logical filter on the predicate field("a").matches(field("b").equals(3)) with an inner FullUnorderedScanExpression.

k

The thisRef parameter has two uses. For some implementations of asUnnestedWith(), the expression does not need to be changed, and so it is more efficient to return the containing reference than to build a new one. Additionally, it is used to generate a reference of the appropriate type using the ExpressionRef.getNewRefWith(PlannerExpression).

Specified by:

asUnnestedWith in interface RelationalPlannerExpression

Parameters:

nestedContext - a context describing the field to use for unnesting

thisRef - the reference that contains this expression

Returns:

a unnested version of this expression with respect to the given context, or null if no such expression exists

equalsWithoutChildren

public boolean equalsWithoutChildren(@Nonnull
                                     PlannerExpression otherExpression)

Specified by:

equalsWithoutChildren in interface PlannerExpression

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object