From 9091ffd7a19992e9ff0797028af1064a57b9bc25 Mon Sep 17 00:00:00 2001
From: skylhd <dickylhd@gmail.com>
Date: Wed, 10 Jan 2024 15:42:41 +0000
Subject: [PATCH] [CP][BUGFIX] fix lrpad mysql pad len zero

---
 src/sql/engine/expr/ob_expr_lrpad.cpp         |  6 +--
 .../static_engine/r/mysql/expr_pad.result     | 43 ++++++++++++++++++-
 .../test_suite/static_engine/t/expr_pad.test  | 13 ++++++
 3 files changed, 58 insertions(+), 4 deletions(-)

diff --git a/src/sql/engine/expr/ob_expr_lrpad.cpp b/src/sql/engine/expr/ob_expr_lrpad.cpp
index 62d7929d23..fa46e1c9ce 100644
--- a/src/sql/engine/expr/ob_expr_lrpad.cpp
+++ b/src/sql/engine/expr/ob_expr_lrpad.cpp
@@ -552,11 +552,11 @@ int ObExprBaseLRpad::calc_mysql_inner(const LRpadType pad_type,
     // only substr needed
     result_size = ObCharset::charpos(cs_type, str_text.ptr(), str_text.length(), int_len);
     res.set_string(ObString(result_size, str_text.ptr()));
+  } else if (str_pad.length() == 0) {
+    res.set_null(); // mysql 5.7 return null while mysql 8.0 return empty string
   } else {
     has_set_to_lob_locator = true;
-    if (str_pad.length() == 0) {
-      res.set_string(ObString::make_empty_string());
-    } else if (OB_FAIL(get_padding_info_mysql(cs_type, str_text, int_len, str_pad,
+    if (OB_FAIL(get_padding_info_mysql(cs_type, str_text, int_len, str_pad,
                 max_result_size, repeat_count, prefix_size, result_size))) {
       LOG_WARN("Failed to get padding info", K(ret), K(str_text), K(int_len),
                                               K(str_pad), K(max_result_size));
diff --git a/tools/deploy/mysql_test/test_suite/static_engine/r/mysql/expr_pad.result b/tools/deploy/mysql_test/test_suite/static_engine/r/mysql/expr_pad.result
index 3e0816bfcb..36c01f16f4 100644
--- a/tools/deploy/mysql_test/test_suite/static_engine/r/mysql/expr_pad.result
+++ b/tools/deploy/mysql_test/test_suite/static_engine/r/mysql/expr_pad.result
@@ -6124,7 +6124,7 @@ select lpad('a', 5, '');
 +------------------+
 | lpad('a', 5, '') |
 +------------------+
-|                  |
+| NULL             |
 +------------------+
 select lpad(NULL, 5, 'a');
 +--------------------+
@@ -6283,3 +6283,44 @@ select rpad('a', 8, '阿斯'), length(rpad('a', 8, '阿斯')) from dual;
 | a阿斯阿斯阿斯阿        |                             22 |
 +------------------------+--------------------------------+
 
+drop table if exists t1;
+create table t1(c1 int);
+insert into t1 values(18);
+select lpad("", cast(c1 as decimal), "") from t1;
++-----------------------------------+
+| lpad("", cast(c1 as decimal), "") |
++-----------------------------------+
+| NULL                              |
++-----------------------------------+
+select lpad("123", cast(c1 as decimal), "") from t1;
++--------------------------------------+
+| lpad("123", cast(c1 as decimal), "") |
++--------------------------------------+
+| NULL                                 |
++--------------------------------------+
+select lpad("", cast(c1 as decimal), "123") from t1;
++--------------------------------------+
+| lpad("", cast(c1 as decimal), "123") |
++--------------------------------------+
+| 123123123123123123                   |
++--------------------------------------+
+select rpad("", cast(c1 as decimal), "") from t1;
++-----------------------------------+
+| rpad("", cast(c1 as decimal), "") |
++-----------------------------------+
+| NULL                              |
++-----------------------------------+
+select rpad("123", cast(c1 as decimal), "") from t1;
++--------------------------------------+
+| rpad("123", cast(c1 as decimal), "") |
++--------------------------------------+
+| NULL                                 |
++--------------------------------------+
+select rpad("", cast(c1 as decimal), "123") from t1;
++--------------------------------------+
+| rpad("", cast(c1 as decimal), "123") |
++--------------------------------------+
+| 123123123123123123                   |
++--------------------------------------+
+drop table t1;
+
diff --git a/tools/deploy/mysql_test/test_suite/static_engine/t/expr_pad.test b/tools/deploy/mysql_test/test_suite/static_engine/t/expr_pad.test
index 97e2b49f1d..4f15d69d65 100644
--- a/tools/deploy/mysql_test/test_suite/static_engine/t/expr_pad.test
+++ b/tools/deploy/mysql_test/test_suite/static_engine/t/expr_pad.test
@@ -116,4 +116,17 @@ select rpad('a', 6, '阿斯'), length(rpad('a', 6, '阿斯')) from dual;
 select rpad('a', 7, '阿斯'), length(rpad('a', 7, '阿斯')) from dual;
 select rpad('a', 8, '阿斯'), length(rpad('a', 8, '阿斯')) from dual;
 
+--disable_warnings
+drop table if exists t1;
+--enable_warnings
+create table t1(c1 int);
+insert into t1 values(18);
+select lpad("", cast(c1 as decimal), "") from t1;
+select lpad("123", cast(c1 as decimal), "") from t1;
+select lpad("", cast(c1 as decimal), "123") from t1;
+select rpad("", cast(c1 as decimal), "") from t1;
+select rpad("123", cast(c1 as decimal), "") from t1;
+select rpad("", cast(c1 as decimal), "123") from t1;
+drop table t1;
+
 --sleep 2