diff --git a/src/sql/engine/expr/ob_expr_repeat.cpp b/src/sql/engine/expr/ob_expr_repeat.cpp
index 1fda797e82..6e11c31706 100644
--- a/src/sql/engine/expr/ob_expr_repeat.cpp
+++ b/src/sql/engine/expr/ob_expr_repeat.cpp
@@ -210,6 +210,9 @@ int ObExprRepeat::repeat_text(ObObjType res_type,
       int64_t tot_length = length * count;
       int64_t buffer_len = 0;
       char *buf = NULL;
+      if (tot_length >= MEM_WARN_THRESHOLD) {
+        LOG_INFO("once repeat cost over 100M", K(ret), K(tot_length), K(length), K(count));
+      }
       ObTextStringResult result_buffer(res_type, has_lob_header, &allocator);
       if (OB_FAIL(result_buffer.init(tot_length))) {
         LOG_WARN("init result failed", K(ret), K(tot_length));
diff --git a/src/sql/engine/expr/ob_expr_repeat.h b/src/sql/engine/expr/ob_expr_repeat.h
index 57901bf5e7..51c2de9794 100644
--- a/src/sql/engine/expr/ob_expr_repeat.h
+++ b/src/sql/engine/expr/ob_expr_repeat.h
@@ -62,6 +62,7 @@ public:
                          ObIAllocator &allocator,
                          const int64_t max_result_size);
 private:
+  static const int64_t MEM_WARN_THRESHOLD = 100 * 1024 * 1024; // 100M
   // disallow copy
   DISALLOW_COPY_AND_ASSIGN(ObExprRepeat);
 };