Package org.elasticsearch.xpack.esql.expression.function.scalar.histogram

Class ExtractHistogramComponent

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.core.expression.function.scalar.ScalarFunction

org.elasticsearch.xpack.esql.expression.function.scalar.EsqlScalarFunction

org.elasticsearch.xpack.esql.expression.function.scalar.histogram.ExtractHistogramComponent

All Implemented Interfaces:

NamedWriteable, Writeable, Resolvable, EvaluatorMapper

public class ExtractHistogramComponent
extends EsqlScalarFunction

Extracts a HistogramBlock.Component from a histogram (either exponential histogram or TDigest). Note that this function is currently only intended for usage in surrogates and not available as a user-facing function. Therefore, it is intentionally not registered in EsqlFunctionRegistry.

Nested Class Summary

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

Expression.TypeResolution

Nested classes/interfaces inherited from interface org.elasticsearch.xpack.esql.evaluator.mapper.EvaluatorMapper

EvaluatorMapper.ToEvaluator

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.core.expression.function.scalar.ScalarFunction

MAX_BYTES_REF_RESULT_SIZE

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

TO_STRING_MAX_WIDTH

Constructor Summary

Constructors

Constructor	Description
ExtractHistogramComponent(Source source, Expression field, Expression componentOrdinal)	Constructor for this function.

Method Summary

Modifier and Type	Method	Description
static Expression	create(Source source, Expression field, HistogramBlock.Component component)
DataType	dataType()	The DataType returned by executing the tree rooted at this expression.
Expression	field()
boolean	foldable()	Whether the expression can be evaluated statically, aka "folded", or not.
String	getWriteableName()
protected NodeInfo<? extends Expression>	info()	Normally, you want to use one of the static create methods to implement this.
Expression	replaceChildren(List<Expression> newChildren)
protected Expression.TypeResolution	resolveType()	The implementation of Expression.typeResolved(), which is just a caching wrapper around this method.
EvalOperator.ExpressionEvaluator.Factory	toEvaluator(EvaluatorMapper.ToEvaluator toEvaluator)	Convert this into an EvalOperator.ExpressionEvaluator.
void	writeTo(StreamOutput out)

Methods inherited from class org.elasticsearch.xpack.esql.expression.function.scalar.EsqlScalarFunction

fold

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

arguments, equals, functionName, hashCode, nodeString, nullable

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

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

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

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

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.elasticsearch.xpack.esql.evaluator.mapper.EvaluatorMapper

fold

Field Details

ENTRY

public static final NamedWriteableRegistry.Entry ENTRY

Constructor Details

ExtractHistogramComponent

public ExtractHistogramComponent(Source source,
 Expression field,
 Expression componentOrdinal)

Constructor for this function.

Parameters:

source - the source

field - the exponential_histogram field to extract the value from

componentOrdinal - The Enum.ordinal() as integer-expression, must be foldable

Method Details

create

public static Expression create(Source source,
 Expression field,
 HistogramBlock.Component component)

field

public Expression field()

writeTo

public void writeTo(StreamOutput out)
             throws IOException

Throws:

IOException

getWriteableName

public String getWriteableName()

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

replaceChildren

public Expression replaceChildren(List<Expression> newChildren)

Specified by:

replaceChildren in class Node<Expression>

info

protected NodeInfo<? extends Expression> 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>

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 Expression

foldable

public boolean foldable()

Description copied from class: Expression

Whether the expression can be evaluated statically, aka "folded", or not.

Overrides:

foldable in class Expression

toEvaluator

public EvalOperator.ExpressionEvaluator.Factory toEvaluator(EvaluatorMapper.ToEvaluator toEvaluator)

Description copied from interface: EvaluatorMapper

Convert this into an EvalOperator.ExpressionEvaluator.

Note for implementors: If you are implementing this function, you should call the passed-in lambda on your children, after doing any other manipulation (casting, etc.) necessary.

Note for Callers: If you are attempting to call this method, and you have an Expression and a Layout, you likely want to call EvalMapper.toEvaluator(org.elasticsearch.xpack.esql.core.expression.FoldContext, org.elasticsearch.xpack.esql.core.expression.Expression, org.elasticsearch.xpack.esql.planner.Layout) instead. On the other hand, if you already have something that looks like the parameter for this method, you should call this method with that function.

Build an EvalOperator.ExpressionEvaluator.Factory for the tree of expressions rooted at this node. This is only guaranteed to return a sensible evaluator if this node has a valid type. If this node is a subclass of Expression then "valid type" means that Expression.typeResolved() returns a non-error resolution. If Expression.typeResolved() returns an error then this method may throw. Or return an evaluator that produces garbage. Or return an evaluator that throws when run.