[Using Sakai] mysql performance issues

[Stephen Marquard]

In mysql, making SAKAI_PRESENCE a memory table could worsen performance issues under heavy load, because it increases contention on the table (counter-intuitively).

So it's not recommended (though there may be out-of-date Confluence documentation that suggests it).

Regards
Stephen 
 

-- 
Stephen Marquard, Acting Director
Centre for Educational Technology, University of Cape Town
http://www.cet.uct.ac.za
Email / IM (Jabber/XMPP): stephen.marquard at uct.ac.za
Phone: +27-21-650-5037 Cell: +27-83-500-5290 


>>> Anders Nordkvist <anders.nordqvist at his.se> 1/17/2012 11:44 AM >>> 
Hi,

Where having performance issues with our mysql 5.1.45 database. I haven't administerd the database from start and I am not very good at mysql. The CPU load is very heavy and it slows down things in Sakai. We have around 400 sessions open at the same time.
To my knowledge the only things that's changed is in my.cnf:

default-storage-engine=InnoDB
innodb_data_file_path=ibdata1:10M:autoextend
innodb_flush_log_at_trx_commit=1
table_open_cache=1024
table_definition_cache=1024
join_buffer_size=131072
max_heap_table_size=67108864
tmp_table_size=67108864
innodb_buffer_pool_size=3221225472

I have looked at the Sakai admin mysql section and found a few tips. One thing to test with is the query caching.
Do you guys have any more tips of how to increase the performance? Do you know of any free profiling tool to use?
My last question is: How do I know that SAKAI_PRESENCE table is in memory?



mvh
Anders Nordqvist
Systemadministratör, Nätbaserad Utbildning
________________________
IT- och campusavdelningen
Högskolan i Skövde
Box 408
541 28 Skövde
tfn 0500-44 81 78
e-post anders.nordqvist at his.se<mailto:fornamn.efternamn at his.se>






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