MySQL Bugs: #10180: Table corruption when two users works with same table without locking

Bug #10180	Table corruption when two users works with same table without locking
Submitted:	26 Apr 2005 15:18	Modified:	27 May 2005 13:50
Reporter:	Sergio Costas	Email Updates:
Status:	No Feedback	Impact on me:	None
Category:	MySQL Server	Severity:	S1 (Critical)
Version:		OS:	Windows (Windows)
Assigned to:	Assigned Account	CPU Architecture:	Any

Description:
I created a program that inserts data from forms into the database. Each time the user ends filling the form, it's sent to MySQL. When only a user works with the table in a local MySQL server, all works fine, but when two users works simultaneously, one in the same computer than the server and the other via network, there occurse serious table corruption.

After adding LOCK and UNLOCK commands in all commands that modifies the tables, the error got fixed. But there should not be needed to do this, since the commands are supposed to be atomic.

It occurred with the last 3.x version of MySQL and the 4.0.x versions. I don't know if it's already fixed because I didn't work more with MySQL.

How to repeat:
Create concurrent reads and writes, one in local and other from a remote computer.

Suggested fix:
no idea.

Hi Sergio,

Would need a bit more info:
- What engine? MyISAM or InnoDB or ..?
- What exact version of MySQL?
- What connectors are used? None or ODBC?
- What kind of table corruption? What is the message returned by CHECK TABLE?

Regards,

Geert

Ops... sorry.

I used MyISAM, and worked directly with your C library. I tried several releases of the 3.23 and 4.0 versions, and all of them had this bug.

About the error returned by CHECK TABLE, I don't remember it exactly, but it was about that one client didn't close the table, like an operation don't finished.

Thanks for your efforts, and sorry if I'm not able to give a more specific info.

Thank you for writting this report.

This bug report forum is only for repeatable bug reports.
What we need is fully repeatable test case.

This test case should consist of the series of SQL commands or actaions that will always lead to the problem, in your case to the crash.

In your case, please send us a set of SQL commands for each of the users that will run those in parallel and produce corruption.

Thanks in advance.

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".