diff --git a/plugins/shard/shard-plugin.c b/plugins/shard/shard-plugin.c
index 26ea0d9..e824628 100644
--- a/plugins/shard/shard-plugin.c
+++ b/plugins/shard/shard-plugin.c
@@ -199,6 +199,13 @@ check_backends_attr_changed(network_mysqld_con *con)
     return server_attr_changed;
 }
 
+static void
+network_mysqld_con_purify_sharding_plan(struct sharding_plan_t *sharding_plan)
+{
+    sharding_plan->modified_sql = NULL;
+    sharding_plan->is_modified = 0;
+}
+
 NETWORK_MYSQLD_PLUGIN_PROTO(proxy_read_query)
 {
     GQueue *chunks = con->client->recv_queue->chunks;
@@ -214,6 +221,9 @@ NETWORK_MYSQLD_PLUGIN_PROTO(proxy_read_query)
 
     p.offset = 0;
     network_mysqld_con_reset_command_response_state(con);
+    if (con->sharding_plan) {
+        network_mysqld_con_purify_sharding_plan(con->sharding_plan);
+    }
     g_debug("%s: call network_mysqld_con_command_states_init", G_STRLOC);
     if (network_mysqld_con_command_states_init(con, &p)) {
         g_warning("%s: tracking mysql proto states failed", G_STRLOC);
@@ -774,6 +784,15 @@ remove_ro_servers(network_mysqld_con *con)
     }
 }
 
+static void
+network_mysqld_con_set_sharding_plan(network_mysqld_con *con, sharding_plan_t *plan)
+{
+    if (con->sharding_plan) {
+        sharding_plan_free(con->sharding_plan);
+    }
+    con->sharding_plan = plan;
+}
+
 static int
 process_init_db_when_get_server_list(network_mysqld_con *con, sharding_plan_t *plan, int *rv, int *disp_flag)
 {
diff --git a/src/network-mysqld.c b/src/network-mysqld.c
index 34cad02..5035b67 100644
--- a/src/network-mysqld.c
+++ b/src/network-mysqld.c
@@ -5026,11 +5026,4 @@ check_and_create_conns_func(int fd, short what, void *arg)
     chassis_event_add_with_timeout(chas, &chas->auto_create_conns_event, &check_interval);
 }
 
-void
-network_mysqld_con_set_sharding_plan(network_mysqld_con *con, sharding_plan_t *plan)
-{
-    if (con->sharding_plan) {
-        sharding_plan_free(con->sharding_plan);
-    }
-    con->sharding_plan = plan;
-}
+
diff --git a/src/network-mysqld.h b/src/network-mysqld.h
index f194b6f..f495437 100644
--- a/src/network-mysqld.h
+++ b/src/network-mysqld.h
@@ -728,11 +728,6 @@ void network_mysqld_send_xa_start(network_socket *, const char *xid);
 NETWORK_API void network_mysqld_con_reset_command_response_state(network_mysqld_con *con);
 NETWORK_API void network_mysqld_con_reset_query_state(network_mysqld_con *con);
 
-/**
- * set groups, delete if already exists
- */
-void network_mysqld_con_set_sharding_plan(network_mysqld_con *con, struct sharding_plan_t *);
-
 /**
  * should be socket 
  */