Esql dimension aware attributes (elastic#131463)

Relates to elastic#128621

This PR adds more building blocks for working with dimensions in ESQL. Specifically, it makes the TSDB metadata available on attributes.

Author: not-napoleon

benchmarks/src/main/java/org/elasticsearch/benchmark/_nightly/esql/QueryPlanningBenchmark.java

@@ -92,7 +92,8 @@ public void setup() {
         var fields = 10_000;
         var mapping = LinkedHashMap.<String, EsField>newLinkedHashMap(fields);
         for (int i = 0; i < fields; i++) {
-            mapping.put("field" + i, new EsField("field-" + i, TEXT, emptyMap(), true));
+            // We're creating a standard index, so none of these fields should be marked as dimensions.
+            mapping.put("field" + i, new EsField("field-" + i, TEXT, emptyMap(), true, EsField.TimeSeriesFieldType.NONE));
         }
 
         var esIndex = new EsIndex("test", mapping, Map.of("test", IndexMode.STANDARD));

benchmarks/src/main/java/org/elasticsearch/benchmark/compute/operator/EvalBenchmark.java

@@ -212,7 +212,7 @@ private static EvalOperator.ExpressionEvaluator evaluator(String operation) {
                 FieldAttribute timestamp = new FieldAttribute(
                     Source.EMPTY,
                     "timestamp",
-                    new EsField("timestamp", DataType.DATETIME, Map.of(), true)
+                    new EsField("timestamp", DataType.DATETIME, Map.of(), true, EsField.TimeSeriesFieldType.NONE)
                 );
                 yield EvalMapper.toEvaluator(
                     FOLD_CONTEXT,
@@ -321,19 +321,35 @@ private static EvalOperator.ExpressionEvaluator evaluator(String operation) {
     }
 
     private static FieldAttribute longField() {
-        return new FieldAttribute(Source.EMPTY, "long", new EsField("long", DataType.LONG, Map.of(), true));
+        return new FieldAttribute(
+            Source.EMPTY,
+            "long",
+            new EsField("long", DataType.LONG, Map.of(), true, EsField.TimeSeriesFieldType.NONE)
+        );
     }
 
     private static FieldAttribute doubleField() {
-        return new FieldAttribute(Source.EMPTY, "double", new EsField("double", DataType.DOUBLE, Map.of(), true));
+        return new FieldAttribute(
+            Source.EMPTY,
+            "double",
+            new EsField("double", DataType.DOUBLE, Map.of(), true, EsField.TimeSeriesFieldType.NONE)
+        );
     }
 
     private static FieldAttribute intField() {
-        return new FieldAttribute(Source.EMPTY, "int", new EsField("int", DataType.INTEGER, Map.of(), true));
+        return new FieldAttribute(
+            Source.EMPTY,
+            "int",
+            new EsField("int", DataType.INTEGER, Map.of(), true, EsField.TimeSeriesFieldType.NONE)
+        );
     }
 
     private static FieldAttribute keywordField() {
-        return new FieldAttribute(Source.EMPTY, "keyword", new EsField("keyword", DataType.KEYWORD, Map.of(), true));
+        return new FieldAttribute(
+            Source.EMPTY,
+            "keyword",
+            new EsField("keyword", DataType.KEYWORD, Map.of(), true, EsField.TimeSeriesFieldType.NONE)
+        );
     }
 
     private static Configuration configuration() {

x-pack/plugin/esql-core/src/main/java/org/elasticsearch/xpack/esql/core/expression/Attribute.java

@@ -149,4 +149,9 @@ public static boolean dataTypeEquals(List<Attribute> left, List<Attribute> right
         }
         return true;
     }
+
+    /**
+     * @return true if the attribute represents a TSDB dimension type
+     */
+    public abstract boolean isDimension();
 }

x-pack/plugin/esql-core/src/main/java/org/elasticsearch/xpack/esql/core/expression/EmptyAttribute.java

@@ -44,6 +44,11 @@ protected String label() {
         return "e";
     }
 
+    @Override
+    public boolean isDimension() {
+        return false;
+    }
+
     @Override
     public boolean resolved() {
         return true;

x-pack/plugin/esql-core/src/main/java/org/elasticsearch/xpack/esql/core/expression/FieldAttribute.java

@@ -216,6 +216,11 @@ protected String label() {
         return "f";
     }
 
+    @Override
+    public boolean isDimension() {
+        return field.getTimeSeriesFieldType() == EsField.TimeSeriesFieldType.DIMENSION;
+    }
+
     public EsField field() {
         return field;
     }

x-pack/plugin/esql-core/src/main/java/org/elasticsearch/xpack/esql/core/expression/MetadataAttribute.java

@@ -120,6 +120,11 @@ protected String label() {
         return "m";
     }
 
+    @Override
+    public boolean isDimension() {
+        return false;
+    }
+
     @Override
     protected NodeInfo<? extends Expression> info() {
         return NodeInfo.create(this, MetadataAttribute::new, name(), dataType(), nullable(), id(), synthetic(), searchable);

x-pack/plugin/esql-core/src/main/java/org/elasticsearch/xpack/esql/core/expression/ReferenceAttribute.java

@@ -117,4 +117,9 @@ protected NodeInfo<ReferenceAttribute> info() {
     protected String label() {
         return "r";
     }
+
+    @Override
+    public boolean isDimension() {
+        return false;
+    }
 }

x-pack/plugin/esql-core/src/main/java/org/elasticsearch/xpack/esql/core/expression/UnresolvedAttribute.java

@@ -107,6 +107,11 @@ protected String label() {
         return UNRESOLVED_PREFIX;
     }
 
+    @Override
+    public boolean isDimension() {
+        return false;
+    }
+
     @Override
     public String nodeString() {
         return toString();

x-pack/plugin/esql-core/src/main/java/org/elasticsearch/xpack/esql/core/type/DateEsField.java

@@ -20,8 +20,8 @@
  */
 public class DateEsField extends EsField {
 
-    public static DateEsField dateEsField(String name, Map<String, EsField> properties, boolean hasDocValues) {
-        return new DateEsField(name, DataType.DATETIME, properties, hasDocValues, TimeSeriesFieldType.UNKNOWN);
+    public static DateEsField dateEsField(String name, Map<String, EsField> properties, boolean hasDocValues, TimeSeriesFieldType tsType) {
+        return new DateEsField(name, DataType.DATETIME, properties, hasDocValues, tsType);
     }
 
     private DateEsField(

x-pack/plugin/esql-core/src/main/java/org/elasticsearch/xpack/esql/core/type/EsField.java

@@ -7,6 +7,7 @@
 package org.elasticsearch.xpack.esql.core.type;
 
 import org.elasticsearch.TransportVersions;
+import org.elasticsearch.action.fieldcaps.IndexFieldCapabilities;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
@@ -31,10 +32,36 @@ public class EsField implements Writeable {
      * roles within the ESQL query processing pipeline.
      */
     public enum TimeSeriesFieldType implements Writeable {
-        UNKNOWN(0),
-        NONE(1),
-        METRIC(2),
-        DIMENSION(3);
+        UNKNOWN(0) {
+            @Override
+            public TimeSeriesFieldType merge(TimeSeriesFieldType other) {
+                return other;
+            }
+        },
+        NONE(1) {
+            @Override
+            public TimeSeriesFieldType merge(TimeSeriesFieldType other) {
+                return other;
+            }
+        },
+        METRIC(2) {
+            @Override
+            public TimeSeriesFieldType merge(TimeSeriesFieldType other) {
+                if (other != DIMENSION) {
+                    return METRIC;
+                }
+                throw new IllegalStateException("Time Series Metadata conflict.  Cannot merge [" + other + "] with [METRIC].");
+            }
+        },
+        DIMENSION(3) {
+            @Override
+            public TimeSeriesFieldType merge(TimeSeriesFieldType other) {
+                if (other != METRIC) {
+                    return DIMENSION;
+                }
+                throw new IllegalStateException("Time Series Metadata conflict.  Cannot merge [" + other + "] with [DIMENSION].");
+            }
+        };
 
         private final int id;
 
@@ -57,6 +84,19 @@ public static TimeSeriesFieldType readFromStream(StreamInput in) throws IOExcept
                 default -> throw new IOException("Unexpected value for TimeSeriesFieldType: " + id);
             };
         }
+
+        public static TimeSeriesFieldType fromIndexFieldCapabilities(IndexFieldCapabilities capabilities) {
+            if (capabilities.isDimension()) {
+                assert capabilities.metricType() == null;
+                return DIMENSION;
+            }
+            if (capabilities.metricType() != null) {
+                return METRIC;
+            }
+            return NONE;
+        }
+
+        public abstract TimeSeriesFieldType merge(TimeSeriesFieldType other);
     }
 
     private static Map<String, Reader<? extends EsField>> readers = Map.ofEntries(
@@ -83,13 +123,8 @@ public static Reader<? extends EsField> getReader(String name) {
     private final Map<String, EsField> properties;
     private final String name;
     private final boolean isAlias;
-    // Because the subclasses all reimplement serialization, this needs to be writeable from subclass constructors
     private final TimeSeriesFieldType timeSeriesFieldType;
 
-    public EsField(String name, DataType esDataType, Map<String, EsField> properties, boolean aggregatable) {
-        this(name, esDataType, properties, aggregatable, false, TimeSeriesFieldType.UNKNOWN);
-    }
-
     public EsField(
         String name,
         DataType esDataType,
@@ -100,10 +135,6 @@ public EsField(
         this(name, esDataType, properties, aggregatable, false, timeSeriesFieldType);
     }
 
-    public EsField(String name, DataType esDataType, Map<String, EsField> properties, boolean aggregatable, boolean isAlias) {
-        this(name, esDataType, properties, aggregatable, isAlias, TimeSeriesFieldType.UNKNOWN);
-    }
-
     public EsField(
         String name,
         DataType esDataType,
@@ -247,6 +278,10 @@ public Exact getExactInfo() {
         return Exact.EXACT_FIELD;
     }
 
+    public TimeSeriesFieldType getTimeSeriesFieldType() {
+        return timeSeriesFieldType;
+    }
+
     @Override
     public String toString() {
         return name + "@" + esDataType.typeName() + "=" + properties;
@@ -265,12 +300,13 @@ public boolean equals(Object o) {
             && isAlias == field.isAlias
             && esDataType == field.esDataType
             && Objects.equals(name, field.name)
-            && Objects.equals(properties, field.properties);
+            && Objects.equals(properties, field.properties)
+            && Objects.equals(timeSeriesFieldType, field.timeSeriesFieldType);
     }
 
     @Override
     public int hashCode() {
-        return Objects.hash(esDataType, aggregatable, properties, name, isAlias);
+        return Objects.hash(esDataType, aggregatable, properties, name, isAlias, timeSeriesFieldType);
     }
 
     public static final class Exact {