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set priority of mysqlDaemon

Posted on 2010-08-19
Medium Priority
Last Modified: 2012-05-10
hi Experts,
Can anyone tell me how to increase the assigned priority to mysqld.exe in a windows system.
I am trying to import and work with a huge huge data set . Each row has only about 5 or 20 columns. The number of rows is huge in millions. The mysqld is using only 25% of CPU on a windows XP machine and returns results after an hour. I am not using a server just  a normal desktop or laptop. I seem to able to increase the priority of mysql.exe but that of mysqld.exe because it is owned by the system? I would like to set it at real time and get back results much faster
thanks for the help
Question by:guyneo
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LVL 79

Expert Comment

ID: 33482110
The issue is likely less to do with the priority/affinity of the process but with the data.
run explain <your query> in either the mysql query browser or using the mysql.exe command line tool.
It should tell you why your query takes this long.
I.e. you may need to add indexes/etc. to optimize the performance of the query

Author Comment

ID: 33484594
This is one time task we are doing for extracting a subset of the data. How long would adding indexes would take on such huge data table?
LVL 79

Accepted Solution

arnold earned 2000 total points
ID: 33485039
Are there existing indexes?  First you need to make sure you have enough space.
Presumably the data will remain and have entries added to it, so it is possible that a similar or other queries will be run against this data.
Was this data set part of a production database that was exported?
Your options are clear and in either case you would need to wait somewhat.
With the query, if you get unexpected results you have to adjust the query and wait just as long, with the addition of the indexes,  you may need to only wait once for the index processing to complete. and then if your initial query does not provide the data that you expect, the next queries might be faster.

There is no way to predict which is more beneficial to you or which less time consuming.
Will your db performance match your db growth?

In Percona’s white paper “Performance at Scale: Keeping Your Database on Its Toes,” we take a high-level approach to what you need to think about when planning for database scalability.


Author Comment

ID: 33495306
I agree indexes would help. I was curious to see if I can get away without index in the first pass. That I am trying trim the useless data out  which might be up to 60-70%. So I thought why create index delete data and recreate data. But lesson learned :) indexes are always faster even though you would need for run a query for only one time  on a huge data set.
Anyway I am still interested to find out if we can increase the mysqld usage of the CPU. I experimented it on various machines, increase the innoDB buffer but it seems to use only upto 35% of the CPU.  Understandle and desirable when everything is one server but when we need to force it to use more, we should be able to. Otherwise thats seems like a waste of time and resources
LVL 79

Expert Comment

ID: 33506330
Allocating processor priority to real time may not improve or speed up the performance of your query/mysql, it may however, distabilize the system to a point of being unusable.

Author Comment

ID: 33517298
Thanks arnold. I realized I should have done indexs right away.
Definitely learnt a couple of new things like explain in  this thread.
I am going to close this question even thoughwe didnot get the answer, I don't think that it is relevant any more.


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