diff --git a/fielddb/field_db.cpp b/fielddb/field_db.cpp
index 93c433c..38e390a 100644
--- a/fielddb/field_db.cpp
+++ b/fielddb/field_db.cpp
@@ -229,6 +229,10 @@ Status FieldDB::CreateIndexOnField(const std::string& field_name) {
     std::string Field = field_name;
     iCreateReq req(&Field,&mutex_);
     HandleRequest(req);
+    //如果已经存在索引，那么可以直接返回
+    if(req.Existed) {
+        return req.s;
+    }
     WriteBatch KVBatch,IndexBatch,MetaBatch;
     req.ConstructBatch(KVBatch, IndexBatch, MetaBatch, this);
     indexDB_->Write(WriteOptions(), &IndexBatch);
@@ -257,6 +261,10 @@ Status FieldDB::DeleteIndex(const std::string &field_name) {
     std::string Field = field_name;
     iDeleteReq req(&Field,&mutex_);
     HandleRequest(req);
+    //如果已经被删除或者不存在，那么可以直接返回
+    if(req.Deleted) {
+        return req.s;
+    }
     WriteBatch KVBatch,IndexBatch,MetaBatch;
     req.ConstructBatch(KVBatch, IndexBatch, MetaBatch, this);
     indexDB_->Write(WriteOptions(), &IndexBatch);
diff --git a/fielddb/request.cpp b/fielddb/request.cpp
index 36d82cf..f601a28 100644
--- a/fielddb/request.cpp
+++ b/fielddb/request.cpp
@@ -104,6 +104,7 @@ void iCreateReq::Prepare(FieldDB *DB) {
         if(istatus == FieldDB::Exist) {
             //如果已经完成建立索引，则返回成功
             done = true;
+            Existed = true;
             s = Status::OK();
         } else {
             //如果正在创建或删除，那么进行等待
@@ -131,4 +132,25 @@ void iCreateReq::Finalize(FieldDB *DB) {
 
 }
 
+/*******iDeleteReq*******/
+void iDeleteReq::Prepare(FieldDB *DB) {
+    DB->index_mu.AssertHeld();
+    if(DB->index_.count(*Field) == 0) {
+        done = true;
+        Deleted = true;
+        s = Status::OK();
+        return ;
+    }
+}
+
+void iDeleteReq::ConstructBatch(WriteBatch &KVBatch,WriteBatch &IndexBatch,
+        WriteBatch &MetaBatch,fielddb::FieldDB *DB)
+{
+
+}
+
+void iDeleteReq::Finalize(FieldDB *DB) {
+
+}
+
 }
\ No newline at end of file
diff --git a/fielddb/request.h b/fielddb/request.h
index 731158d..3346c1f 100644
--- a/fielddb/request.h
+++ b/fielddb/request.h
@@ -87,13 +87,14 @@ public:
 class iCreateReq : public Request {
 public:
     iCreateReq(std::string *Field,port::Mutex *mu):
-        Field(Field),Request(iCreateReq_t, mu) { };
+        Field(Field),Request(iCreateReq_t, mu),Existed(false) { };
 
     void ConstructBatch(WriteBatch &KVBatch,WriteBatch &IndexBatch,
         WriteBatch &MetaBatch,fielddb::FieldDB *DB) override;
     void Prepare(FieldDB *DB) override;
     void Finalize(FieldDB *DB) override;
         
+    bool Existed;
     std::string *Field;
     std::deque<Request *> pending_list;
 };
@@ -102,13 +103,14 @@ public:
 class iDeleteReq : public Request {
 public:
     iDeleteReq(std::string *Field,port::Mutex *mu):
-        Field(Field),Request(iDeleteReq_t, mu) { };
+        Field(Field),Request(iDeleteReq_t, mu),Deleted(false) { };
 
     void ConstructBatch(WriteBatch &KVBatch,WriteBatch &IndexBatch,
         WriteBatch &MetaBatch,fielddb::FieldDB *DB) override;
     void Prepare(FieldDB *DB) override;
     void Finalize(FieldDB *DB) override;
-    
+
+    bool Deleted;
     std::string *Field;
     std::deque<Request *> pending_list;
 };