diff --git a/deps/oblib/src/lib/mysqlclient/ob_mysql_connection.cpp b/deps/oblib/src/lib/mysqlclient/ob_mysql_connection.cpp
index 916b8a2df5..e0466d60ad 100644
--- a/deps/oblib/src/lib/mysqlclient/ob_mysql_connection.cpp
+++ b/deps/oblib/src/lib/mysqlclient/ob_mysql_connection.cpp
@@ -234,6 +234,15 @@ int ObMySQLConnection::connect(const char *user, const char *pass, const char *d
       LOG_WARN("fail to connect to mysql server", K(get_sessid()), KCSTRING(host), KCSTRING(user), KCSTRING(db), K(port),
                "info", mysql_error(&mysql_), K(ret));
       if (OB_INVALID_ID != get_dblink_id()) {
+        LOG_WARN("dblink connection error", K(ret),
+                                            KP(this),
+                                            K(get_dblink_id()),
+                                            K(get_sessid()),
+                                            K(usable()),
+                                            K(user),
+                                            K(db),
+                                            K(host),
+                                            K(port));
         TRANSLATE_CLIENT_ERR_2(ret, false, mysql_error(&mysql_));
       }
     } else {
diff --git a/deps/oblib/src/lib/mysqlclient/ob_mysql_result.cpp b/deps/oblib/src/lib/mysqlclient/ob_mysql_result.cpp
index 38a8b1b0b7..f0174ac9f4 100644
--- a/deps/oblib/src/lib/mysqlclient/ob_mysql_result.cpp
+++ b/deps/oblib/src/lib/mysqlclient/ob_mysql_result.cpp
@@ -86,12 +86,20 @@ int ObMySQLResult::format_precision_scale_length(int16_t &precision, int16_t &sc
   // format precision from others to oceanbase
   if (!lib::is_oracle_mode()) {
     switch (ob_type) {
-      case ObUNumberType:
-      case ObNumberType: { // for mysql decimal
-        if (2 == length) {
-          precision = 1;
+      case ObUNumberType:{
+        if (0 != scale) {
+          precision = length - 1;// remove length of decimal point
         } else {
-           precision = length - 1;
+          precision = length;
+        }
+        length = -1;
+        break;
+      }
+      case ObNumberType: {
+        if (0 != scale) {
+          precision = length - 2;// remove length of decimal point and sign(-/+)
+        } else {
+          precision = length - 1;// remove length of decimal point
         }
         length = -1;
         break;
diff --git a/deps/oblib/src/lib/mysqlclient/ob_mysql_result_impl.cpp b/deps/oblib/src/lib/mysqlclient/ob_mysql_result_impl.cpp
index 4601115a97..631cd25823 100644
--- a/deps/oblib/src/lib/mysqlclient/ob_mysql_result_impl.cpp
+++ b/deps/oblib/src/lib/mysqlclient/ob_mysql_result_impl.cpp
@@ -23,6 +23,7 @@
 #include "common/ob_zerofill_info.h"
 #include "lib/timezone/ob_timezone_info.h"
 #include "lib/string/ob_hex_utils_base.h"
+#include "lib/mysqlclient/ob_dblink_error_trans.h"
 
 namespace oceanbase
 {
@@ -143,7 +144,33 @@ int ObMySQLResultImpl::next()
     ret = OB_ERR_UNEXPECTED;
     LOG_ERROR("result must not be null", K(ret));
   } else if (OB_ISNULL(cur_row_ = mysql_fetch_row(result_))) {
-    ret = OB_ITER_END;
+    MYSQL *stmt_handler = stmt_.get_stmt_handler();
+    if (OB_ISNULL(stmt_handler)) {
+      ret = OB_ERR_UNEXPECTED;
+      LOG_WARN("unexpected null ptr", K(ret));
+    } else {
+      ret = -mysql_errno(stmt_handler);
+      const char *errmsg = mysql_error(stmt_handler);
+      ObMySQLConnection *conn = stmt_.get_connection();
+      if (0 == ret) {
+        ret = OB_ITER_END;
+      } else if (OB_ISNULL(conn)) {
+        int tmp_ret = ret;
+        ret = OB_ERR_UNEXPECTED;
+        LOG_WARN("unexpected null ptr", K(errmsg), K(tmp_ret), K(ret));
+      } else if (OB_INVALID_ID != conn->get_dblink_id()) {
+        LOG_WARN("dblink connection error", K(ret),
+                                            KP(conn),
+                                            K(conn->get_dblink_id()),
+                                            K(conn->get_sessid()),
+                                            K(conn->usable()),
+                                            K(conn->ping()));
+        TRANSLATE_CLIENT_ERR(ret, errmsg);
+        if (ObMySQLStatement::is_need_disconnect_error(ret)) {
+          conn->set_usable(false);
+        }
+      }
+    }
   } else if (OB_ISNULL(cur_row_result_lengths_ = mysql_fetch_lengths(result_))) {
     ret = OB_ERR_UNEXPECTED;
     LOG_WARN("calling is out of sync", K(ret));
diff --git a/deps/oblib/src/lib/mysqlclient/ob_mysql_statement.cpp b/deps/oblib/src/lib/mysqlclient/ob_mysql_statement.cpp
index 8ef4153474..7ce9f5fceb 100644
--- a/deps/oblib/src/lib/mysqlclient/ob_mysql_statement.cpp
+++ b/deps/oblib/src/lib/mysqlclient/ob_mysql_statement.cpp
@@ -108,6 +108,17 @@ int ObMySQLStatement::execute_update(int64_t &affected_rows)
         conn_->get_root()->get_root()->signal_refresh(); // refresh server pool immediately
       }
       if (OB_INVALID_ID != conn_->get_dblink_id()) {
+        LOG_WARN("dblink connection error", K(ret),
+                                            KP(conn_),
+                                            K(conn_->get_dblink_id()),
+                                            K(conn_->get_sessid()),
+                                            K(conn_->usable()),
+                                            K(conn_->ping()),
+                                            K(stmt_->host),
+                                            K(stmt_->port),
+                                            K(mysql_error(stmt_)),
+                                            K(STRLEN(sql_str_)),
+                                            K(sql_str_));
         TRANSLATE_CLIENT_ERR(ret, mysql_error(stmt_));
       }
       if (is_need_disconnect_error(ret)) {
@@ -151,6 +162,17 @@ ObMySQLResult *ObMySQLStatement::execute_query(bool enable_use_result)
         ret = OB_ERR_SQL_CLIENT;
         LOG_WARN("can not get errno", K(ret));
       } else if (OB_INVALID_ID != conn_->get_dblink_id()) {
+        LOG_WARN("dblink connection error", K(ret),
+                                            KP(conn_),
+                                            K(conn_->get_dblink_id()),
+                                            K(conn_->get_sessid()),
+                                            K(conn_->usable()),
+                                            K(conn_->ping()),
+                                            K(stmt_->host),
+                                            K(stmt_->port),
+                                            K(mysql_error(stmt_)),
+                                            K(STRLEN(sql_str_)),
+                                            K(sql_str_));
         TRANSLATE_CLIENT_ERR(ret, mysql_error(stmt_));
       }
       if (is_need_disconnect_error(ret)) {
diff --git a/deps/oblib/src/lib/mysqlclient/ob_mysql_statement.h b/deps/oblib/src/lib/mysqlclient/ob_mysql_statement.h
index 1b825a4647..9a40d9e792 100644
--- a/deps/oblib/src/lib/mysqlclient/ob_mysql_statement.h
+++ b/deps/oblib/src/lib/mysqlclient/ob_mysql_statement.h
@@ -50,7 +50,7 @@ public:
    * but ignore affected_rows
    */
   int execute_update();
-  bool is_need_disconnect_error(int ret);
+  static bool is_need_disconnect_error(int ret);
 
   /*
    * ! Deprecated