Package org.elasticsearch.xpack.esql.core.expression

Class Attribute

java.lang.Object

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

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

org.elasticsearch.xpack.esql.core.expression.NamedExpression

org.elasticsearch.xpack.esql.core.expression.Attribute

All Implemented Interfaces:

NamedWriteable, Writeable, Resolvable

Direct Known Subclasses:

EmptyAttribute, TypedAttribute, UnresolvedAttribute

public abstract class Attribute
extends NamedExpression

Expressions that can be materialized and describe properties of the derived table. In other words, an attribute represent a column in the results of a query.

In the statement SELECT ABS(foo), A, B+C FROM ... the three named expressions ABS(foo), A, B+C get converted to attributes and the user can only see Attributes.

In the statement SELECT foo FROM TABLE WHERE foo > 10 + 1 only foo inside the SELECT is a named expression (an Alias will be created automatically for it). The rest are not as they are not part of the projection and thus are not part of the derived table.

Note on equality: Because the name alone is not sufficient to identify an attribute (two different relations can have the same attribute name), attributes get a unique NamedExpression.id() assigned at creation which is respected in equality checks and hashing.

Caution! semanticEquals(Expression) and semanticHash() rely solely on the id. But this doesn't extend to expressions containing attributes as children.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static final record	Attribute.IdIgnoringWrapper	A wrapper class where equality of the contained attribute ignores the NamedExpression.id().

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

Modifier and Type	Field	Description
protected static final String	SYNTHETIC_ATTRIBUTE_NAME_PREFIX	Changing this will break bwc with 8.15, see FieldAttribute.fieldName().

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

TO_STRING_MAX_WIDTH

Constructor Summary

Constructors

Constructor	Description
Attribute(Source source, String qualifier, String name, NameId id)
Attribute(Source source, String qualifier, String name, Nullability nullability, NameId id)
Attribute(Source source, String qualifier, String name, Nullability nullability, NameId id, boolean synthetic)
Attribute(Source source, String name, NameId id)
Attribute(Source source, String name, Nullability nullability, NameId id)
Attribute(Source source, String name, Nullability nullability, NameId id, boolean synthetic)

Method Summary

Modifier and Type	Method	Description
protected Expression	canonicalize()
protected void	checkAndSerializeQualifier(PlanStreamOutput out, TransportVersion version)
protected abstract Attribute	clone(Source source, String qualifier, String name, DataType type, Nullability nullability, NameId id, boolean synthetic)
static boolean	dataTypeEquals(List<Attribute> left, List<Attribute> right)	Compares the size and datatypes of two lists of attributes for equality.
Attribute.IdIgnoringWrapper	ignoreId()
protected boolean	innerEquals(Object o, boolean ignoreIds)	The actual equality check, after shortcutting this == o and class checks.
protected int	innerHashCode(boolean ignoreIds)
abstract boolean	isDimension()
abstract boolean	isMetric()
protected abstract String	label()
String	nodeString()
Nullability	nullable()
String	qualifiedName()
String	qualifier()
static String	rawTemporaryName(String... parts)
protected static String	readQualifier(PlanStreamInput in, TransportVersion version)
AttributeSet	references()	Set of Attributes referenced by this Expression.
final Expression	replaceChildren(List<Expression> newChildren)
boolean	semanticEquals(Expression other)	Whether this expression means the same as other, even if they are not exactly equal.
int	semanticHash()	A hash code that is consistent with Expression.semanticEquals(org.elasticsearch.xpack.esql.core.expression.Expression).
Attribute	toAttribute()	Try to return either this if it is an Attribute, or a ReferenceAttribute to it otherwise.
String	toString()
Attribute	withDataType(DataType type)
Attribute	withId(NameId id)
Attribute	withLocation(Source source)
Attribute	withName(String name)
Attribute	withNullability(Nullability nullability)
Attribute	withQualifier(String qualifier)

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

equals, equals, hashCode, hashCode, id, name, synthetic

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

canonical, childrenResolved, dataType, fold, foldable, propertiesToString, resolved, resolveType, typeResolved

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

anyMatch, children, collect, collectFirstChildren, collectLeaves, doCollectFirst, forEachDown, forEachDown, forEachDownMayReturnEarly, forEachProperty, forEachPropertyDown, forEachPropertyOnly, forEachPropertyUp, forEachUp, forEachUp, info, 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.common.io.stream.NamedWriteable

getWriteableName

Methods inherited from interface org.elasticsearch.common.io.stream.Writeable

writeTo

Field Details

SYNTHETIC_ATTRIBUTE_NAME_PREFIX

protected static final String SYNTHETIC_ATTRIBUTE_NAME_PREFIX

Changing this will break bwc with 8.15, see FieldAttribute.fieldName().

See Also:

• Constant Field Values

Constructor Details

Attribute

public Attribute(Source source,
 String name,
 @Nullable
 NameId id)

Attribute

public Attribute(Source source,
 @Nullable
 String qualifier,
 String name,
 @Nullable
 NameId id)

Attribute

public Attribute(Source source,
 String name,
 Nullability nullability,
 @Nullable
 NameId id)

Attribute

public Attribute(Source source,
 @Nullable
 String qualifier,
 String name,
 Nullability nullability,
 @Nullable
 NameId id)

Attribute

public Attribute(Source source,
 String name,
 Nullability nullability,
 @Nullable
 NameId id,
 boolean synthetic)

Attribute

public Attribute(Source source,
 @Nullable
 String qualifier,
 String name,
 Nullability nullability,
 @Nullable
 NameId id,
 boolean synthetic)

Method Details

ignoreId

public Attribute.IdIgnoringWrapper ignoreId()

rawTemporaryName

public static String rawTemporaryName(String... parts)

replaceChildren

public final Expression replaceChildren(List<Expression> newChildren)

Specified by:

replaceChildren in class Node<Expression>

qualifier

public String qualifier()

qualifiedName

public String qualifiedName()

nullable

public Nullability nullable()

Specified by:

nullable in class Expression

references

public AttributeSet references()

Description copied from class: Expression

Set of Attributes referenced by this Expression.

Overrides:

references in class Expression

withLocation

public Attribute withLocation(Source source)

withQualifier

public Attribute withQualifier(String qualifier)

withName

public Attribute withName(String name)

withNullability

public Attribute withNullability(Nullability nullability)

withId

public Attribute withId(NameId id)

withDataType

public Attribute withDataType(DataType type)

clone

protected abstract Attribute clone(Source source,
 String qualifier,
 String name,
 DataType type,
 Nullability nullability,
 NameId id,
 boolean synthetic)

toAttribute

public Attribute toAttribute()

Description copied from class: NamedExpression

Try to return either this if it is an Attribute, or a ReferenceAttribute to it otherwise. Return an UnresolvedAttribute if this is unresolved.

Specified by:

toAttribute in class NamedExpression

semanticHash

public int semanticHash()

Description copied from class: Expression

A hash code that is consistent with Expression.semanticEquals(org.elasticsearch.xpack.esql.core.expression.Expression).

Overrides:

semanticHash in class Expression

semanticEquals

public boolean semanticEquals(Expression other)

Description copied from class: Expression

Whether this expression means the same as other, even if they are not exactly equal. For example, a + b and b + a are not equal, but they are semantically equal.

If two expressions are equal, they are also semantically equal, but the reverse is generally not true.

Caution! semanticEquals(Expression) is especially lenient, as it considers two attributes with the same NameId to be semantically equal, even if they have different data types or are represented using different classes.

But this doesn't extend to expressions containing attributes as children, which is pretty inconsistent. We have to revisit this before using Expression.semanticEquals(org.elasticsearch.xpack.esql.core.expression.Expression) in more places.

Overrides:

semanticEquals in class Expression

canonicalize

protected Expression canonicalize()

Overrides:

canonicalize in class Expression

innerHashCode

protected int innerHashCode(boolean ignoreIds)

Overrides:

innerHashCode in class NamedExpression

innerEquals

protected boolean innerEquals(Object o,
 boolean ignoreIds)

Description copied from class: NamedExpression

The actual equality check, after shortcutting this == o and class checks.

Overrides:

innerEquals in class NamedExpression

toString

public String toString()

Overrides:

toString in class NamedExpression

nodeString

public String nodeString()

Overrides:

nodeString in class NamedExpression

label

protected abstract String label()

dataTypeEquals

public static boolean dataTypeEquals(List<Attribute> left,
 List<Attribute> right)

Compares the size and datatypes of two lists of attributes for equality.

isDimension

public abstract boolean isDimension()

Returns:

true if the attribute represents a TSDB dimension type

isMetric

public abstract boolean isMetric()

Returns:

true if the attribute represents a TSDB metric type

checkAndSerializeQualifier

protected void checkAndSerializeQualifier(PlanStreamOutput out,
 TransportVersion version)
                                   throws IOException

Throws:

IOException

readQualifier

protected static String readQualifier(PlanStreamInput in,
 TransportVersion version)
                               throws IOException

Throws:

IOException