MySQL Bugs: #29609: 0 length string update does not work on varchar variables;

Bug #29609	0 length string update does not work on varchar variables;
Submitted:	7 Jul 2007 8:23	Modified:	7 Aug 2007 11:46
Reporter:	Farzin Rezaeian	Email Updates:
Status:	No Feedback	Impact on me:	None
Category:	MySQL Server: InnoDB storage engine	Severity:	S2 (Serious)
Version:	5.0.15-nt-log	OS:	Windows (show variables included)
Assigned to:		CPU Architecture:	Any

Description:
combination of infile read into table and subsequent insert and update of values with 0 length string result in inconsistency. 
On consistent updates with 0 length string causes mysqld crashes.
Complete test case is included.

How to repeat:
mysql> create table testb (a BIGINT(20) unsigned NOT NULL default 0,b VARCHAR (255) DEFAULT NULL);
Query OK, 0 rows affected (0.06 sec)

mysql> select * from testb;
Empty set (0.00 sec)

mysql> load data infile 'D:\\testbug.txt' into table testb Fields terminated by '_#_' Lines terminated by '_LINEBREAK_' Ig
nore 1 Lines (a,b);
Query OK, 2 rows affected (0.00 sec)
Records: 2  Deleted: 0  Skipped: 0  Warnings: 0

mysql> select * from testb;
+--------+------+
| a      | b    |
+--------+------+
|      1 | NULL |
| 123456 | NULL |
+--------+------+
2 rows in set (0.00 sec)

mysql> insert into testb (a) values(100);
Query OK, 1 row affected (0.02 sec)

mysql> select * from testb;
+--------+------+
| a      | b    |
+--------+------+
|      1 | NULL |
| 123456 | NULL |
|    100 | NULL |
+--------+------+
3 rows in set (0.00 sec)

mysql> update testb set b="";
Query OK, 3 rows affected (0.02 sec)
Rows matched: 3  Changed: 3  Warnings: 0

mysql> select * from testb;
+--------+------+
| a      | b    |
+--------+------+
|      1 |      |
| 123456 |      |
|    100 | NULL |
+--------+------+
3 rows in set (0.00 sec)

mysql>

testb.txt source:
a_#_b_LINEBREAK_1_#_NULL_LINEBREAK_123456_#_NULL_LINEBREAK_

Suggested fix:
Please help with this bug as I am currently stalling on my project because of this bug, or kindely tell me how to avoid it.

source file

Attachment: testbug.txt (text/plain), 59 bytes.

variables of system

Attachment: show variables.txt (text/plain), 21.34 KiB.

Thank you for the report.

But version 5.0.15 is quite old. Additionally I can not repeat described behavior with current development sources. Please upgrade to current version 5.0.41, try with it and say us result.

No feedback was provided for this bug for over a month, so it is
being suspended automatically. If you are able to provide the
information that was originally requested, please do so and change
the status of the bug back to "Open".