refactor(server): optimize rockdb batch query perf

hugegraph-server/hugegraph-core/src/main/java/org/apache/hugegraph/backend/tx/GraphTransaction.java

@@ -783,8 +783,10 @@ protected Iterator<Vertex> queryVerticesByIds(Object[] vertexIds, boolean adjace
         // NOTE: allowed duplicated vertices if query by duplicated ids
         List<Id> ids = InsertionOrderUtil.newList();
         Map<Id, HugeVertex> vertices = new HashMap<>(vertexIds.length);
+        Set<Id> fetchedIds = InsertionOrderUtil.newSet();
+        IdQuery batchQuery = null;
+        final int batchSize = this.batchSize;
 
-        IdQuery query = new IdQuery(type);
         for (Object vertexId : vertexIds) {
             HugeVertex vertex;
             Id id = HugeVertex.getIdValue(vertexId);
@@ -799,17 +801,25 @@ protected Iterator<Vertex> queryVerticesByIds(Object[] vertexIds, boolean adjace
                 // Found from local tx
                 vertices.put(vertex.id(), vertex);
             } else {
-                // Prepare to query from backend store
-                query.query(id);
+                // Query from backend
+                if (!fetchedIds.contains(id)) {
+                    if (batchQuery == null) {
+                        batchQuery = new IdQuery(type);
+                    }
+                    batchQuery.query(id);
+                    fetchedIds.add(id);
+
+                    if (batchQuery.idsSize() >= batchSize) {
+                        flushIdBatch(batchQuery, vertices);
+                        batchQuery = null;
+                    }
+                }
             }
             ids.add(id);
         }
 
-        if (!query.empty()) {
-            // Query from backend store
-            query.mustSortByInput(false);
-            Iterator<HugeVertex> it = this.queryVerticesFromBackend(query);
-            QueryResults.fillMap(it, vertices);
+        if (batchQuery != null && !batchQuery.empty()) {
+            flushIdBatch(batchQuery, vertices);
         }
 
         return new MapperIterator<>(ids.iterator(), id -> {
@@ -831,6 +841,13 @@ protected Iterator<Vertex> queryVerticesByIds(Object[] vertexIds, boolean adjace
         });
     }
 
+    private void flushIdBatch(IdQuery query, Map<Id, HugeVertex> vertices) {
+        Query.checkForceCapacity(query.idsSize());
+        query.mustSortByInput(false);
+        Iterator<HugeVertex> it = this.queryVerticesFromBackend(query);
+        QueryResults.fillMap(it, vertices);
+    }
+
     public Iterator<Vertex> queryVertices() {
         Query q = new Query(HugeType.VERTEX);
         return this.queryVertices(q);

hugegraph-server/hugegraph-rocksdb/src/main/java/org/apache/hugegraph/backend/store/rocksdb/RocksDBTable.java

@@ -309,7 +309,7 @@ protected static BackendEntryIterator newEntryIterator(BackendColumnIterator col
     }
 
     protected static BackendEntryIterator newEntryIteratorOlap(
-        BackendColumnIterator cols, Query query, boolean isOlap) {
+            BackendColumnIterator cols, Query query, boolean isOlap) {
         return new BinaryEntryIterator<>(cols, query, (entry, col) -> {
             if (entry == null || !entry.belongToMe(col)) {
                 HugeType type = query.resultType();