checkpoint

Author: not-napoleon

server/src/main/java/org/elasticsearch/TransportVersions.java

@@ -302,7 +302,7 @@ static TransportVersion def(int id) {
     public static final TransportVersion SECURITY_CLOUD_API_KEY_REALM_AND_TYPE = def(9_099_0_00);
     public static final TransportVersion STATE_PARAM_GET_SNAPSHOT = def(9_100_0_00);
     public static final TransportVersion PROJECT_ID_IN_SNAPSHOTS_DELETIONS_AND_REPO_CLEANUP = def(9_101_0_00);
-
+    public static final TransportVersion ESQL_SERIALIZE_TIMESERIES_FIELD_TYPE = def(9_102_0_00);
     /*
      * STOP! READ THIS FIRST! No, really,
      *        ____ _____ ___  ____  _        ____  _____    _    ____    _____ _   _ ___ ____    _____ ___ ____  ____ _____ _

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

@@ -6,6 +6,7 @@
  */
 package org.elasticsearch.xpack.esql.core.type;
 
+import org.elasticsearch.TransportVersions;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 
@@ -30,13 +31,21 @@ private DateEsField(String name, DataType dataType, Map<String, EsField> propert
 
     protected DateEsField(StreamInput in) throws IOException {
         this(readCachedStringWithVersionCheck(in), DataType.DATETIME, in.readImmutableMap(EsField::readFrom), in.readBoolean());
+        if (in.getTransportVersion().onOrAfter(TransportVersions.ESQL_SERIALIZE_TIMESERIES_FIELD_TYPE)) {
+            this.timeSeriesFieldType = TimeSeriesFieldType.readFromStream(in);
+        } else {
+            this.timeSeriesFieldType = TimeSeriesFieldType.UNKNOWN;
+        }
     }
 
     @Override
     public void writeContent(StreamOutput out) throws IOException {
         writeCachedStringWithVersionCheck(out, getName());
         out.writeMap(getProperties(), (o, x) -> x.writeTo(out));
         out.writeBoolean(isAggregatable());
+        if (out.getTransportVersion().onOrAfter(TransportVersions.ESQL_SERIALIZE_TIMESERIES_FIELD_TYPE)) {
+            this.timeSeriesFieldType.writeTo(out);
+        }
     }
 
     public String getWriteableName() {

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

@@ -26,7 +26,40 @@
  */
 public class EsField implements Writeable {
 
-    private static Map<String, Writeable.Reader<? extends EsField>> readers = Map.ofEntries(
+    /**
+     * Fields in a TSDB can be either dimensions or metrics.  This enum provides a way to store, serialize, and operate on those field
+     * roles within the ESQL query processing pipeline.
+     */
+    public enum TimeSeriesFieldType implements Writeable {
+        UNKNOWN(0),
+        NONE(1),
+        METRIC(2),
+        DIMENSION(3);
+
+        private final int id;
+
+        TimeSeriesFieldType(int id) {
+            this.id = id;
+        }
+
+        @Override
+        public void writeTo(StreamOutput out) throws IOException {
+            out.writeVInt(id);
+        }
+
+        public static TimeSeriesFieldType readFromStream(StreamInput in) throws IOException {
+            int id = in.readVInt();
+            return switch (id) {
+                case 0 -> UNKNOWN;
+                case 1 -> NONE;
+                case 2 -> METRIC;
+                case 3 -> DIMENSION;
+                default -> throw new IOException("Unexpected value for TimeSeriesFieldType: " + id);
+            };
+        }
+    }
+
+    private static Map<String, Reader<? extends EsField>> readers = Map.ofEntries(
         Map.entry("DateEsField", DateEsField::new),
         Map.entry("EsField", EsField::new),
         Map.entry("InvalidMappedField", InvalidMappedField::new),
@@ -37,7 +70,7 @@ public class EsField implements Writeable {
         Map.entry("UnsupportedEsField", UnsupportedEsField::new)
     );
 
-    public static Writeable.Reader<? extends EsField> getReader(String name) {
+    public static Reader<? extends EsField> getReader(String name) {
         Reader<? extends EsField> result = readers.get(name);
         if (result == null) {
             throw new IllegalArgumentException("Invalid EsField type [" + name + "]");
@@ -50,6 +83,8 @@ public static Writeable.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
+    protected TimeSeriesFieldType timeSeriesFieldType;
 
     public EsField(String name, DataType esDataType, Map<String, EsField> properties, boolean aggregatable) {
         this(name, esDataType, properties, aggregatable, false);
@@ -61,6 +96,7 @@ public EsField(String name, DataType esDataType, Map<String, EsField> properties
         this.aggregatable = aggregatable;
         this.properties = properties;
         this.isAlias = isAlias;
+        this.timeSeriesFieldType = TimeSeriesFieldType.UNKNOWN;
     }
 
     public EsField(StreamInput in) throws IOException {
@@ -69,6 +105,11 @@ public EsField(StreamInput in) throws IOException {
         this.properties = in.readImmutableMap(EsField::readFrom);
         this.aggregatable = in.readBoolean();
         this.isAlias = in.readBoolean();
+        if (in.getTransportVersion().onOrAfter(TransportVersions.ESQL_SERIALIZE_TIMESERIES_FIELD_TYPE)) {
+            this.timeSeriesFieldType = TimeSeriesFieldType.readFromStream(in);
+        } else {
+            this.timeSeriesFieldType = TimeSeriesFieldType.UNKNOWN;
+        }
     }
 
     private DataType readDataType(StreamInput in) throws IOException {
@@ -107,6 +148,9 @@ public void writeContent(StreamOutput out) throws IOException {
         out.writeMap(properties, (o, x) -> x.writeTo(out));
         out.writeBoolean(aggregatable);
         out.writeBoolean(isAlias);
+        if (out.getTransportVersion().onOrAfter(TransportVersions.ESQL_SERIALIZE_TIMESERIES_FIELD_TYPE)) {
+            this.timeSeriesFieldType.writeTo(out);
+        }
     }
 
     /**

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

@@ -6,6 +6,7 @@
  */
 package org.elasticsearch.xpack.esql.core.type;
 
+import org.elasticsearch.TransportVersions;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.core.Tuple;
@@ -35,6 +36,11 @@ public TextEsField(String name, Map<String, EsField> properties, boolean hasDocV
 
     protected TextEsField(StreamInput in) throws IOException {
         this(readCachedStringWithVersionCheck(in), in.readImmutableMap(EsField::readFrom), in.readBoolean(), in.readBoolean());
+        if (in.getTransportVersion().onOrAfter(TransportVersions.ESQL_SERIALIZE_TIMESERIES_FIELD_TYPE)) {
+            this.timeSeriesFieldType = TimeSeriesFieldType.readFromStream(in);
+        } else {
+            this.timeSeriesFieldType = TimeSeriesFieldType.UNKNOWN;
+        }
     }
 
     @Override
@@ -43,6 +49,9 @@ public void writeContent(StreamOutput out) throws IOException {
         out.writeMap(getProperties(), (o, x) -> x.writeTo(out));
         out.writeBoolean(isAggregatable());
         out.writeBoolean(isAlias());
+        if (out.getTransportVersion().onOrAfter(TransportVersions.ESQL_SERIALIZE_TIMESERIES_FIELD_TYPE)) {
+            this.timeSeriesFieldType.writeTo(out);
+        }
     }
 
     public String getWriteableName() {