Re: Often corrupt table indexes

[oliver]

Hi Ingo,

I am sorry that i cannot giv you any *nix* applications to repeat the error, but i think i have some good (or maybe bad considering the circumstances) news for you: I am still using a Windows System to transform our logfiles and issue all the SQL-Statements, but I have tried several serverhardware in the meantime. I took MySQL release 4.1.12 and installed

- Compaq Proliant 5000 (2 Pentium Pro 200 CPU) / Read Hat Linux
- Siemens N400 (4 Intel Xeon CPU) / Windows 2000
- HP Proliant DL 380G4 (2 Xeon Dual Core CPU) / Windows 2003
- HP Proliant DL 380G4 (2 Xeon Dual Core CPU) / Red Hat Linux
- AMD 64 System running Windows XP (Single CPU)
- Pentium III Red Hat Linux
- Pentium IV Windows XP

(Thanks to my employer for providing the hardware and manpower;-)))

Result: After two day of testing I have not been able to produce the error on any single CPU System but I have several times been able to produce the error on every multiple cpu system. There is also another remarkable thing: The faster the CPUs get, the more likely you get the error. In fact the error occured only 3 times on the Proliant 5000, 12 times on the N400 15 times on the DL3800 W2k3 and 16 times on the DL380 RedHat.

There is one more thing: There seems to be a direct link between the speed of your sending the SQL Commands and the chance to get the error. I have never been able to produce it on either of the DL380 if I just hacked the commands on the Query Browser (laps between commands let's say about 20 seconds). Only if the commands come directly after each other (application or SQL Script).

And another one: You always get descriptions like

+------------------------+-------+----------+-----------------------------+
| Table | Op | Msg_type | Msg_text |
+------------------------+-------+----------+-----------------------------+
| auswertung_05 | check | warning | Table is marked as crashed |
| auswertung_05 | check | error | Found 385318 keys of 387149 |
| auswertung_05 | check | error | Corrupt |
+------------------------+-------+----------+-----------------------------+

meaning check table is always finding less key entries than it should.


Puuh, long writiging but what I wanted to say is: The error is not depending on the OS version of MySQL you are using (at least not Windows and Red Hat). It is depeding on the number and speed of the cpu's used in the system, so I am really convinced it must be a synchronisation problem between at least two different threads in the server application.

I am still trying to optimize the sample application so that you will have a preferably short way to go to produce the error. I'll get back to you when I'm ready.

Regards,
Oliver