List:General Discussion« Previous MessageNext Message »
From:Andrew Morgan Date:December 18 2012 5:47pm
Subject:Re: MySQL Cluster alerts
View as plain text  
Hi Bheemsen,

 looks like a few different things going on there; if you have a MySQL support
contract/subscription then it would be worth raising SRs - it doesn't need to be a bug,
it's fine tyo ask questions too. A couple of things that spring to mind in-line....

> I am frequently seeing the following alerts in our production MySQL Cluster
> environment. Do you have any metrics, guidelines and scripts to monitor and
> fix these alerts? Any help is appreciated.
> Temporary Tables To Disk Ratio Excessive
> Excessive Disk Temporary Table Usage Detected
> Table Scans Excessive
> Indexes Not Being Used Efficiently

If you're using MySQL Cluster 7.2 then you should run OPTIMIZE TABLE for each of your
tables (repeat that step whenever you make schemas changes to it, add an index or make
very signifficant data changes). This will make the optimizer make better use of available
indexes. Use the query analyzer in MySQL Enterprise Monitor (MEM) to see which queries are
taking the time as these are likely to be the table scans (full table scans should be
avoided as much as possible). You can use the EXPLAIN command to see if individual queries
are making use of the available indexes. Try adding new indexes if they're missing for
high-running transactions.

> Thread Cache Size May Not Be Optimal
> Cluster DiskPageBuffer Hit Ratio Is Low

Note that you might observe this after restarting a data node as the cache must be
repopulated as queries come in. If you're seeing this at other times or the MEM graphs
show that the DiskPageBuffer Hit Ratio is consistently low then consider increasing it...

MySQL Cluster alertsBheemsen Aitha16 Dec
Re: MySQL Cluster alertsAndrew Morgan18 Dec