feat(server): Add vector index

hugegraph-server/hugegraph-api/src/main/java/org/apache/hugegraph/api/schema/IndexLabelAPI.java

@@ -235,6 +235,13 @@ public void checkCreate(boolean isBatch) {
             E.checkArgumentNotNull(this.indexType,
                                    "The index type of index label '%s' " +
                                    "can't be null", this.name);
+            if(this.indexType == IndexType.VECTOR){
+                E.checkArgumentNotNull(this.userdata,
+                                       "The user_data(dimension and metric) of vector index " +
+                                       "label '%s' " +
+                                       "can't be null", this.name);
+            }
+
         }
 
         @Override

hugegraph-server/hugegraph-core/src/main/java/org/apache/hugegraph/schema/Userdata.java

@@ -20,8 +20,10 @@
 import java.util.HashMap;
 import java.util.Map;
 
+import org.apache.hugegraph.backend.id.Id;
 import org.apache.hugegraph.exception.NotAllowException;
 import org.apache.hugegraph.type.define.Action;
+import org.apache.hugegraph.util.E;
 
 public class Userdata extends HashMap<String, Object> {
 
@@ -61,4 +63,10 @@ public static void check(Userdata userdata, Action action) {
                         "Unknown schema action '%s'", action));
         }
     }
+
+    public static void checkDimensionAndMetric(Userdata userdata) {
+        E.checkArgument((userdata.get("dimension") != null) &&
+                        (userdata.get("metric") != null),
+                        "The vector index dimension and metric can't not be null");
+    }
 }

hugegraph-server/hugegraph-core/src/main/java/org/apache/hugegraph/schema/builder/IndexLabelBuilder.java

@@ -43,6 +43,7 @@
 import org.apache.hugegraph.schema.VertexLabel;
 import org.apache.hugegraph.type.HugeType;
 import org.apache.hugegraph.type.define.Action;
+import org.apache.hugegraph.type.define.Cardinality;
 import org.apache.hugegraph.type.define.CollectionType;
 import org.apache.hugegraph.type.define.DataType;
 import org.apache.hugegraph.type.define.IndexType;
@@ -390,6 +391,11 @@ public IndexLabelBuilder unique() {
         return this;
     }
 
+    public IndexLabelBuilder vector() {
+        this.indexType = IndexType.VECTOR;
+        return this;
+    }
+
     @Override
     public IndexLabelBuilder on(HugeType baseType, String baseValue) {
         E.checkArgument(baseType == HugeType.VERTEX_LABEL ||
@@ -526,6 +532,21 @@ private void checkFields(Set<Id> propertyIds) {
                             "Search index can only build on text property, " +
                             "but got %s(%s)", dataType, field);
         }
+
+        // Vector index must build on float list
+        if(this.indexType.isVector()){
+            E.checkArgument(fields.size() == 1,
+                            "vector index can only build on " +
+                            "one field, but got %s fields: '%s'",
+                            fields.size(), fields);
+            String field = fields.iterator().next();
+            DataType dataType = this.graph().propertyKey(field).dataType();
+            Cardinality cardinality = this.graph().propertyKey(field).cardinality();
+            E.checkArgument((dataType == DataType.FLOAT) &&
+                                      (cardinality == Cardinality.LIST),
+                            "vector index can only build on Float List, " +
+                            "but got %s(%s)", dataType, cardinality);
+        }
     }
 
     private void checkFields4Range() {
@@ -587,6 +608,9 @@ private void checkRepeatIndex(SchemaLabel schemaLabel) {
             case UNIQUE:
                 this.checkRepeatUniqueIndex(schemaLabel);
                 break;
+            case VECTOR:
+                this.checkRepeatVectorIndex(schemaLabel);
+                break;
             default:
                 throw new AssertionError(String.format(
                         "Unsupported index type: %s", this.indexType));
@@ -675,6 +699,11 @@ private void checkRepeatShardIndex(SchemaLabel schemaLabel) {
         }
     }
 
+    private void checkRepeatVectorIndex(SchemaLabel schemaLabel) {
+        this.checkRepeatIndex(schemaLabel, IndexType.VECTOR);
+    }
+
+
     private void checkRepeatUniqueIndex(SchemaLabel schemaLabel) {
         this.checkRepeatIndex(schemaLabel, List::containsAll, IndexType.UNIQUE);
     }

hugegraph-server/hugegraph-core/src/main/java/org/apache/hugegraph/type/HugeType.java

@@ -64,6 +64,7 @@ public enum HugeType implements SerialEnum {
     SEARCH_INDEX(170, "AI"),
     SHARD_INDEX(175, "HI"),
     UNIQUE_INDEX(178, "UI"),
+    VECTOR_INDEX(180, "VI"),
 
     TASK(180, "TASK"),
     SERVER(181, "SERVER"),

hugegraph-server/hugegraph-core/src/main/java/org/apache/hugegraph/type/define/IndexType.java

@@ -38,7 +38,10 @@ public enum IndexType implements SerialEnum {
     SHARD(4, "shard"),
 
     // For unique index
-    UNIQUE(5, "unique");
+    UNIQUE(5, "unique"),
+
+    //For vector index
+    VECTOR(6, "vector");
 
     private byte code = 0;
     private String name = null;
@@ -80,6 +83,8 @@ public HugeType type() {
                 return HugeType.SHARD_INDEX;
             case UNIQUE:
                 return HugeType.UNIQUE_INDEX;
+            case VECTOR:
+                return HugeType.VECTOR_INDEX;
             default:
                 throw new AssertionError(String.format(
                         "Unknown index type '%s'", this));
@@ -117,4 +122,8 @@ public boolean isShard() {
     public boolean isUnique() {
         return this == UNIQUE;
     }
+
+    public boolean isVector() {
+        return this == VECTOR;
+    }
 }