MySQL Bugs: #10307: MyIsam table crashes randomly

Bug #10307	MyIsam table crashes randomly
Submitted:	2 May 2005 8:46	Modified:	1 Sep 2005 9:09
Reporter:	Lars Thiele	Email Updates:
Status:	No Feedback	Impact on me:	None
Category:	MySQL Server: MyISAM storage engine	Severity:	S2 (Serious)
Version:	4.1.10	OS:	Linux (suse 9.2)
Assigned to:	Assigned Account	CPU Architecture:	Any

Description:
I have a great problem with using MyISAM tables with more than one blob field.
I am using the MySQL C API, and Mysql server 4.1.10 on a Suse 9.2.
My table contains 12 blob fields and some varchar fields, with a total size of 600MB.
I already posted a thread into the forum (MyIsam) http://forums.mysql.com/read.php?21,24167,24167#msg-24167.

The problem that occurs is:
1. When doing a SELECT on that tabel I randomly get the error 127. (the user that does the selects does not have writing permissions)
2. When doing a mysql check table TABLE, the table gets marked as crashed.
3. Repairing results in data loss.

Flushing the tables or reseting the mysqld doesn't help anything.
I already tried dumping the table and reloaded it, but with no effect.
I upgraded from a MySQL server version 4.0.22, there the error appeared much more often.

BUT: when I am clearing the systems memory (virtual & real, by doing a restart of my system or using a c++ program allocating a lot of memory) before doing a check table, every thing is fine. And the error disappeared!
(when I force mysql, operating system to relaod everything!)

I did a memory test, with no error resulting!

What could be the problem (the hardware, suse 9.2, MySQl itself)?

Thank you guys for your suggested solutions.

How to repeat:
random error (one error in 80 selects)
by using tables approx. 600MB in size.

Suggested fix:
Since the problem seems to be located in the memory handling, i could split the data over a few tables. But thats not the solution I want to use, because it makes the system hardly manageable.

if possible please upload the table to our FTP server (using a filename that includes the bug number).

your data will be used for debugging purposes only and won't be visible to anyone but MySQL staff

o.k. I can do this, where should I put this table. Can you give the ftp-address, please.
Is a normal mysqldump enough?

thanks in advance

You can upload the dump file at:

ftp://ftp.mysql.com/pub/mysql/upload/

Thank you in advance.

Now I uploaded the dump file to that ftp directory.

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".

Hi Lars,

Thank you for the table.  Have you found a way to repeat the problem
reliably?  Possibly a particular statement or group of them that you run
repeatadly?  Could you provide those if so?

Thanks!

I am doing SELECT statements on that table with the mysql c-api. I can put my  c++ source code or the SELECT statements here if it would help.
thanks Lars.

yes, please attach the c++ file, and we'll try to reproduce it

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".