diff --git a/docs/developer_guides/chap06_root_coordinator.md b/docs/developer_guides/chap06_root_coordinator.md
index 7233d81616..cc9285e113 100644
--- a/docs/developer_guides/chap06_root_coordinator.md
+++ b/docs/developer_guides/chap06_root_coordinator.md
@@ -637,19 +637,16 @@ _tenantMetaBlob_, _proxyMetaBlob_, _collectionInfoBlob_, _partitionInfoBlob_, _I
 
 ```go
 type metaTable struct {
-	client             kv.SnapShotKV
-	tenantID2Meta      map[typeutil.UniqueID]pb.TenantMeta
-	proxyID2Meta       map[typeutil.UniqueID]pb.ProxyMeta
-	collID2Meta        map[typeutil.UniqueID]pb.CollectionInfo
-	collName2ID        map[string]typeutil.UniqueID
-	partitionID2Meta   map[typeutil.UniqueID]pb.PartitionInfo
-	segID2IndexMeta    map[typeutil.UniqueID]*map[typeutil.UniqueID]pb.SegmentIndexInfo
-	indexID2Meta       map[typeutil.UniqueID]pb.IndexInfo
-	segID2CollID       map[typeutil.UniqueID]typeutil.UniqueID
-	segID2PartitionID  map[typeutil.UniqueID]typeutil.UniqueID
-	flushedSegID       map[typeutil.UniqueID]bool
-	partitionID2CollID map[typeutil.UniqueID]typeutil.UniqueID
-	vChan2Chan         map[string]string
+	txn             kv.TxnKV                                                        // client of a reliable txnkv service, i.e. etcd client
+	snapshot        kv.SnapShotKV                                                   // client of a reliable snapshotkv service, i.e. etcd client
+	tenantID2Meta   map[typeutil.UniqueID]pb.TenantMeta                             // tenant id to tenant meta
+	proxyID2Meta    map[typeutil.UniqueID]pb.ProxyMeta                              // proxy id to proxy meta
+	collID2Meta     map[typeutil.UniqueID]pb.CollectionInfo                         // collection_id -> meta
+	collName2ID     map[string]typeutil.UniqueID                                    // collection name to collection id
+	collAlias2ID    map[string]typeutil.UniqueID                                    // collection alias to collection id
+	partID2SegID    map[typeutil.UniqueID]map[typeutil.UniqueID]bool                // partition_id -> segment_id -> bool
+	segID2IndexMeta map[typeutil.UniqueID]map[typeutil.UniqueID]pb.SegmentIndexInfo // collection_id/index_id/partition_id/segment_id -> meta
+	indexID2Meta    map[typeutil.UniqueID]pb.IndexInfo                              // collection_id/index_id -> meta
 
 	tenantLock sync.RWMutex
 	proxyLock  sync.RWMutex