[GE users] mysql path + arco issues

aja alena.plestilova at sun.com
Tue Feb 17 12:35:42 GMT 2009


Hi Cris,

crhea wrote:
> On Fri, Feb 13, 2009 at 08:53:29AM +0100, aja wrote:
>   
>> http://gridengine.sunsource.net/howto/arco/arco_mysql.txt ?
>> You can find useful information there.
>> Especially, do not forget to configure MySQL server to use InnoDB as the 
>> default storage engine!
>>
>> Regards,
>> aja
>>     
>
> A question and an issue for the Arco gurus...
>
> 1. Back when we installed Arco, the install guide made little distinction 
>    on the engine used for MySQL. From Aja's comments above, it appears that
>    this is a big deal. What features/engine characteristics is Arco 
>    using where InnoDB matters over the default (MyISAM)?
>
>    (My current cluster/Arco uses MyISAM and I want to understand if 
>    it's worth it to convert the tables to InnoDB...)
>
>   
The storage engine should support transactions, MyISAM does not support 
them.

> 2. If dbwriter dies (for whatever reason), we've seen that the cleanup process
>    never catches up. In poking around, we see (for example):
>
>    SELECT hv_id FROM sge_host_values WHERE hv_time_end < '2008-02-16 14:00:00' limit 500
>
>     as a sub-select of a DELETE. Why is the SQL code structured this way?
>     On a small-medium cluster (100 nodes/400 CPUs) the sub-select can take
>     several minutes to run (our sge_host_values table is 110M rows). 
>     Why limit each sub-select to 500?  When we get into this state, the 
>     cleanup never catches up and thrashes the DB.  I go in by hand and 
>     run the delete with a WHERE clause (no sub-select, no limit). 
>
> Thanks--
>
> -- Cris
>
>   
The limit was added due to the issue 
http://gridengine.sunsource.net/issues/show_bug.cgi?id=2284.
I don't have much experience with Mysql database so I will appreciate 
yours, do you think it won't cause any problem when the limit is removed 
from delete statement for Mysql?
If you have problems with deleting data I can recommend to disable 
deletion rules and delete them manually or write a script which would do it.

Regards,
aja

-- 
aja & sun
e-mail: aja at sun.com

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