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

Class CompletionFunction

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.inference.InferenceFunction<CompletionFunction>

org.elasticsearch.xpack.esql.expression.function.inference.CompletionFunction

All Implemented Interfaces:

NamedWriteable, Writeable, Resolvable

public class CompletionFunction
extends InferenceFunction<CompletionFunction>

COMPLETION function generates text completions from a prompt using an inference endpoint.

This function is an internal optimization primitive used exclusively for constant folding of COMPLETION commands during the analysis phase. It should never be registered in the function registry or exposed to users, as ESQL does not currently support async functions in the function registry.

When a COMPLETION command has a foldable prompt (e.g., a literal or foldable expression), the analyzer transforms it into an EVAL node with a CompletionFunction expression:

 FROM books
 | COMPLETION "Translate this text" WITH { "inference_id": "my-model" }
 

is internally rewritten into:

 FROM books
 | EVAL completion = COMPLETION("Translate this text", "my-model")
 

The pre-optimizer then evaluates this function using InferenceFunctionEvaluator and replaces it with a literal result.

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.common.io.stream.Writeable

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

Field Summary

Fields inherited from class org.elasticsearch.xpack.esql.expression.function.inference.InferenceFunction

INFERENCE_ID_PARAMETER_NAME

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

TO_STRING_MAX_WIDTH

Constructor Summary

Constructors

Constructor	Description
CompletionFunction(Source source, Expression prompt, Expression inferenceId)

Method Summary

Modifier and Type	Method	Description
DataType	dataType()	The DataType returned by executing the tree rooted at this expression.
boolean	equals(Object o)
boolean	foldable()	Whether the expression can be evaluated statically, aka "folded", or not.
String	getWriteableName()
int	hashCode()
Expression	inferenceId()	The inference endpoint identifier expression.
protected NodeInfo<? extends Expression>	info()	Normally, you want to use one of the static create methods to implement this.
Expression	prompt()
Expression	replaceChildren(List<Expression> newChildren)
protected Expression.TypeResolution	resolveType()	The implementation of Expression.typeResolved(), which is just a caching wrapper around this method.
TaskType	taskType()	The task type required by this function (e.g., TEXT_EMBEDDING).
String	toString()
CompletionFunction	withInferenceResolutionError(String inferenceId, String error)	Returns a copy with inference resolution error for display to user.
void	writeTo(StreamOutput out)

Methods inherited from class org.elasticsearch.xpack.esql.expression.function.inference.InferenceFunction

hasNestedInferenceFunction

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, propertiesToString, references, resolved, semanticEquals, semanticHash, 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

Constructor Details

CompletionFunction

public CompletionFunction(Source source,
 Expression prompt,
 Expression inferenceId)

Method Details

writeTo

public void writeTo(StreamOutput out)
             throws IOException

Throws:

IOException

getWriteableName

public String getWriteableName()

prompt

public Expression prompt()

inferenceId

public Expression inferenceId()

Description copied from class: InferenceFunction

The inference endpoint identifier expression.

Specified by:

inferenceId in class InferenceFunction<CompletionFunction>

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

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 Expression

taskType

public TaskType taskType()

Description copied from class: InferenceFunction

The task type required by this function (e.g., TEXT_EMBEDDING).

Specified by:

taskType in class InferenceFunction<CompletionFunction>

withInferenceResolutionError

public CompletionFunction withInferenceResolutionError(String inferenceId,
 String error)

Description copied from class: InferenceFunction

Returns a copy with inference resolution error for display to user.

Specified by:

withInferenceResolutionError in class InferenceFunction<CompletionFunction>

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>

toString

public String toString()

Overrides:

toString in class Expression

equals

public boolean equals(Object o)

Overrides:

equals in class Function

hashCode

public int hashCode()

Overrides:

hashCode in class Function