Bug #115954 Confusing warning "Cannot add field x in table y because after adding it ..."

Description:
Supposedly we end up with a table with a definition violating the row limit. It can happen after upgrading from MySQL 5.6 where innodb_strict_mode was by default disabled or the strict mode is disabled explicitly. The said warning, for example:
[Warning] [MY-011825] [InnoDB] Cannot add field `c11` in table `test`.`test` because after adding it, the row size is 8872 which is greater than maximum allowed size (8126) for a record on index leaf page.
is logged not only when one tries to alter the table (and add a new column as the message suggests), but also on the following other occasions:
* CREATE TABLE
* ALTER TABLE ... DROP COLUMN (even if dropping actually allows it to fit into size restrictions)
* Loading the table object into the table definition cache

I consider this report to be an extension to https://bugs.mysql.com/bug.php?id=113695

How to repeat:
mysql > select @@version;
+-----------+
| @@version |
+-----------+
| 8.4.2     |
+-----------+
1 row in set (0.00 sec)

mysql > set session innodb_strict_mode=0;
Query OK, 0 rows affected (0.00 sec)

mysql > CREATE TABLE `test` (
    ->  `c1` varchar(255),
    ->  `c2` varchar(255),
    ->  `c3` varchar(255),
    ->  `c4` varchar(255),
    ->  `c5` varchar(255),
    ->  `c6` varchar(255),
    ->  `c7` varchar(255),
    ->  `c8` varchar(255),
    ->  `c9` varchar(255),
    ->  `c10` varchar(255),
    ->  `c11` varchar(255),
    ->   PRIMARY KEY (`c1`(40))
    -> ) ENGINE=InnoDB ROW_FORMAT=COMPACT;
Query OK, 0 rows affected, 1 warning (0.03 sec)

mysql > show warnings\G
*************************** 1. row ***************************
  Level: Warning
   Code: 139
Message: Row size too large (> 8126). Changing some columns to TEXT or BLOB or using ROW_FORMAT=DYNAMIC or ROW_FORMAT=COMPRESSED may help. In current row format, BLOB prefix of 768 bytes is stored inline.
1 row in set (0.00 sec)

Error log new entry:
2024-08-28T14:55:50.916840Z 8 [Warning] [MY-011825] [InnoDB] Cannot add field `c11` in table `test`.`test` because after adding it, the row size is 8872 which is greater than maximum allowed size (8126) for a record on index leaf page.

mysql > set session innodb_strict_mode=1;
Query OK, 0 rows affected (0.00 sec)

mysql > insert into test set c1="foobar";
Query OK, 1 row affected (0.00 sec)

-- Restart the server and try to access the table:
mysql > select c1 from test;
+--------+
| c1     |
+--------+
| foobar |
+--------+
1 row in set, 1 warning (0.09 sec)

mysql > show warnings\G
*************************** 1. row ***************************
  Level: Warning
   Code: 139
Message: Row size too large (> 8126). Changing some columns to TEXT or BLOB or using ROW_FORMAT=DYNAMIC or ROW_FORMAT=COMPRESSED may help. In current row format, BLOB prefix of 768 bytes is stored inline.
1 row in set (0.00 sec)

And again the same in error log:
2024-08-28T15:08:28.982806Z 8 [Warning] [MY-011825] [InnoDB] Cannot add field `c11` in table `test`.`test` because after adding it, the row size is 8872 which is greater than maximum allowed size (8126) for a record on index leaf page.

Another select, as the table object is already loaded, does not trigger the warning again:
mysql > select c1 from test;
+--------+
| c1     |
+--------+
| foobar |
+--------+
1 row in set (0.00 sec)

Removing the culprit column works without any warning:
mysql > alter table test drop column c11;
Query OK, 0 rows affected (0.13 sec)
Records: 0  Duplicates: 0  Warnings: 0

But surprisingly, the confusing error is printed into the log:
2024-08-28T15:11:39.717489Z 8 [ERROR] [MY-011825] [InnoDB] Cannot add field `c11` in table `test`.`test` because after adding it, the row size is 8872 which is greater than maximum allowed size (8126) for a record on index leaf page.

Suggested fix:
I think it would be more appropriate to log a more customized message instead of "Cannot add field" in each of these cases. It is certainly odd to read this when we only read from the table or drop a column.

Hello Przemyslaw,

Thank you for the report and feedback. 
Verified as described.

Thanks,
Umesh

Posted by developer:
 
Added the following note to the MySQL Server 8.0.44, 8.4.7, and 9.5.0 release notes:
	
If the row size exceeded the maximum allowed size due to innodb_strict_mode=OFF,
confusing warning messages similar to "Cannot add field" could appear in certain
situations, such as selecting from a table or dropping a column.
Error messages are improved for this scenario.