Package org.elasticsearch.xpack.esql.expression.function.aggregate

Class Scalar

java.lang.Object

org.elasticsearch.xpack.esql.core.tree.Node<Expression>

org.elasticsearch.xpack.esql.core.expression.Expression

org.elasticsearch.xpack.esql.core.expression.function.Function

org.elasticsearch.xpack.esql.expression.function.aggregate.AggregateFunction

org.elasticsearch.xpack.esql.expression.function.aggregate.Scalar

All Implemented Interfaces:

NamedWriteable, Writeable, PostAnalysisPlanVerificationAware, Resolvable, SurrogateExpression

public class Scalar
extends AggregateFunction
implements SurrogateExpression

Returns the sample value if there is exactly one element, otherwise returns NaN.

Nested Class Summary

Nested classes/interfaces inherited from class org.elasticsearch.xpack.esql.core.expression.Expression

Expression.TypeResolution

Nested classes/interfaces inherited from class org.elasticsearch.xpack.esql.core.tree.Node

Node.NodeStringFormat

Nested classes/interfaces inherited from interface org.elasticsearch.common.io.stream.Writeable

Writeable.Reader<V>, Writeable.Writer<V>

Field Summary

Fields

Modifier and Type	Field	Description
static final NamedWriteableRegistry.Entry	ENTRY

Fields inherited from class org.elasticsearch.xpack.esql.expression.function.aggregate.AggregateFunction

NO_WINDOW, WINDOW_INTERVAL

Fields inherited from class org.elasticsearch.xpack.esql.core.tree.Node

TO_STRING_MAX_LINES, TO_STRING_MAX_WIDTH

Constructor Summary

Constructors

Constructor	Description
Scalar(Source source, Expression field)
Scalar(Source source, Expression field, Expression filter, Expression window)

Method Summary

Modifier and Type	Method	Description
DataType	dataType()	The DataType returned by executing the tree rooted at this expression.
String	getWriteableName()
protected NodeInfo<Scalar>	info()	Normally, you want to use one of the static create methods to implement this.
Scalar	replaceChildren(List<Expression> newChildren)
protected Expression.TypeResolution	resolveType()	The implementation of Expression.typeResolved(), which is just a caching wrapper around this method.
Expression	surrogate()	Returns the expression to be replaced by or null if this cannot be replaced.
AggregateFunction	withFilter(Expression filter)	Attach a filter to the aggregate function.

Methods inherited from class org.elasticsearch.xpack.esql.expression.function.aggregate.AggregateFunction

aggregateInputReferences, equals, field, filter, hasFilter, hashCode, hasWindow, parameters, postAnalysisPlanVerification, readWindow, window, withField, withFilter, withFilter, withParameters, withWindow, writeTo

Methods inherited from class org.elasticsearch.xpack.esql.core.expression.function.Function

arguments, functionName, nodeString, nullable

Methods inherited from class org.elasticsearch.xpack.esql.core.expression.Expression

canonical, canonicalize, childrenResolved, fold, foldable, propertiesToString, references, resolved, semanticEquals, semanticHash, toString, toString, typeResolved

Methods inherited from class org.elasticsearch.xpack.esql.core.tree.Node

allMatch, anyMatch, children, collect, collect, collect, collectFirstChildren, collectLeaves, doCollectFirst, forEachDown, forEachDown, forEachDownMayReturnEarly, forEachProperty, forEachPropertyDown, forEachPropertyOnly, forEachPropertyUp, forEachUp, forEachUp, nodeName, nodeProperties, nodeString, replaceChildrenSameSize, source, sourceLocation, sourceText, transformChildren, transformChildren, transformDown, transformDown, transformDown, transformDown, transformDownSkipBranch, transformNodeProps, transformPropertiesDown, transformPropertiesOnly, transformPropertiesUp, transformUp, transformUp, transformUp

Methods inherited from class java.lang.Object

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

Field Details

ENTRY

public static final NamedWriteableRegistry.Entry ENTRY

Constructor Details

Scalar

public Scalar(Source source,
 Expression field)

Scalar

public Scalar(Source source,
 Expression field,
 Expression filter,
 Expression window)

Method Details

getWriteableName

public String getWriteableName()

Specified by:

getWriteableName in interface NamedWriteable

info

protected NodeInfo<Scalar> info()

Description copied from class: Node

Normally, you want to use one of the static create methods to implement this.

For QueryPlans, it is very important that the properties contain all of the expressions and references relevant to this node, and that all the properties are used in the provided constructor; otherwise query plan transformations like QueryPlan#transformExpressionsOnly(Function) will not have an effect.

Specified by:

info in class Node<Expression>

withFilter

public AggregateFunction withFilter(Expression filter)

Description copied from class: AggregateFunction

Attach a filter to the aggregate function.

Specified by:

withFilter in class AggregateFunction

replaceChildren

public Scalar replaceChildren(List<Expression> newChildren)

Specified by:

replaceChildren in class Node<Expression>

dataType

public DataType dataType()

Description copied from class: Expression

The DataType returned by executing the tree rooted at this expression. If Expression.typeResolved() returns an error then the behavior of this method is undefined. It may return a valid type. Or it may throw an exception. Or it may return a totally nonsensical type.

Specified by:

dataType in class Expression

resolveType

protected Expression.TypeResolution resolveType()

Description copied from class: Expression

The implementation of Expression.typeResolved(), which is just a caching wrapper around this method. See it's javadoc for what this method should return.

Implementations will rarely interact with the Expression.TypeResolution class directly, instead usually calling the utility methods on TypeResolutions.

Implementations should fail if Expression.childrenResolved() returns false.

Overrides:

resolveType in class AggregateFunction

surrogate

public Expression surrogate()

Description copied from interface: SurrogateExpression

Returns the expression to be replaced by or null if this cannot be replaced.

Specified by:

surrogate in interface SurrogateExpression