diff --git a/src/sql/engine/expr/ob_expr_compress.cpp b/src/sql/engine/expr/ob_expr_compress.cpp
index d00a3552fe..d11534db7e 100644
--- a/src/sql/engine/expr/ob_expr_compress.cpp
+++ b/src/sql/engine/expr/ob_expr_compress.cpp
@@ -141,7 +141,8 @@ static int eval_uncompress_length(const ObExpr &expr,
 {
   int ret = OB_SUCCESS;
   if (str_val.empty()) {
-    expr_datum.set_string(ObString::make_empty_string());
+    orig_len = 0;
+    not_final = true;
   } else if (OB_UNLIKELY((str_val.length() <= COMPRESS_HEADER_LEN))) {
     expr_datum.set_null();
     LOG_USER_WARN(OB_ERR_ZLIB_DATA);
@@ -188,14 +189,18 @@ int ObExprUncompress::eval_uncompress(const ObExpr &expr, ObEvalCtx &ctx, ObDatu
       int64_t buf_size = 0;
       if (OB_FAIL(output_result.init(orig_len))) {
         LOG_WARN("init stringtext result failed");
-      } else if (OB_FAIL(output_result.get_reserved_buffer(buf, buf_size))) {
-        LOG_WARN("stringtext result reserve buffer failed");
-      } else if (OB_UNLIKELY(Z_OK != uncompress(reinterpret_cast<unsigned char*>(buf), &orig_len,
-          reinterpret_cast<const unsigned char*>(str_val.ptr() + COMPRESS_HEADER_LEN), str_val.length()))) {
-        expr_datum.set_null();
-        LOG_USER_WARN(OB_ERR_ZLIB_DATA);
-      } else if (OB_FAIL(output_result.lseek(orig_len, 0))) {
-        LOG_WARN("result lseek failed", K(ret));
+      } else if (orig_len > 0) {
+        if (OB_FAIL(output_result.get_reserved_buffer(buf, buf_size))) {
+          LOG_WARN("stringtext result reserve buffer failed");
+        } else if (OB_UNLIKELY(Z_OK != uncompress(reinterpret_cast<unsigned char*>(buf), &orig_len,
+            reinterpret_cast<const unsigned char*>(str_val.ptr() + COMPRESS_HEADER_LEN), str_val.length()))) {
+          expr_datum.set_null();
+          LOG_USER_WARN(OB_ERR_ZLIB_DATA);
+        } else if (OB_FAIL(output_result.lseek(orig_len, 0))) {
+          LOG_WARN("result lseek failed", K(ret));
+        } else {
+          output_result.set_result();
+        }
       } else {
         output_result.set_result();
       }