tshipley@deru.com wrote:
> In generic terms the database 101 class would say analyze your query to see if you can finagle the efficiency. A lot of reports link queries at the report/sub-report level, so look at the algorithm there.
>
> It is EASY to have a critical report that brings a system to its knees. Therefore, with any scale and $, DBAs replicate data from the transaction server to a report server. The report server doubles as a backup.
> Sent from my BlackBerry Smartphone provided by Alltel
>
> -----Original Message-----
> From: Joshua Zeidner <jjzeidner@gmail.com>
>
> Date: Wed, 8 Jul 2009 12:23:15
> To: Main PLUG discussion list<plug-discuss@lists.plug.phoenix.az.us>
> Subject: Re: PHP Script timing out and MySql using almost all the CPU and RAM
> questions
>
>
> sounds like you have either a MySQl bug or a problem query. Turn on
> query logging and get the query that is causing the problem and post
> it here.
>
> -jmz
>
> On Wed, Jul 8, 2009 at 12:21 PM, keith smith<klsmith2020@yahoo.com> wrote:
>>
>> Hi Everyone,
>>
>> I do support for an online store.
>>
>> Last night we were trying to run a report that was taking forever. It is a lot of data so I expected it to timeout. The owner says he has successfully run the report before. I shelled in and found MySql was using 98.3% of the CPU and I think 4.7% of Memory.
>>
>> I restarted MySql and the load went down to nothing.
>>
>> While I was in there I noticed we have 513764k of RAM, and we were using almost all of it and we were using some swap as well.
>>
>> Here is what I just pulled off the system.
>>
>> top - 11:12:54 up 229 days, 20:08, 3 users, load average: 0.21, 0.16, 0.07
>> Tasks: 80 total, 2 running, 78 sleeping, 0 stopped, 0 zombie
>> Cpu(s): 1.0%us, 0.3%sy, 0.0%ni, 95.7%id, 0.0%wa, 3.0%hi, 0.0%si, 0.0%st
>> Mem: 513764k total, 506652k used, 7112k free, 4904k buffers
>> Swap: 3723784k total, 32276k used, 3691508k free, 311520k cached
>>
>>
>> This raises a number of questions:
>>
>> 1) What could cause the MySql server to start using so much CPU? After a restart we ran the report again and the CPU usage was much less. The report still timed out.
>>
>> 2) I'm wondering if more RAM would make the system more responsive? I've seen the benefits of RAM first hand but not in how it would speed up a web server.
>>
>> 3) The report we were running gave no indication of timing out. I'm wondering how the following PHP.ini directives come into play:
>>
>> - max_execution_time = 30 : In seconds. Why would the script appear to keep working?
>>
>> - max_input_time = 60 : Same question as above.
>>
>> I'm wondering if setting the memory - ini_set('memory_limit', '64M'); in that app, if that would help much and if I extend the time if that might help - ini_set('max_execution_time',240); along with ini_set("max_input_time", 240) ?
>>
>> Thanks in advance for your help!
>>
>> ------------------------
>> Keith Smith
>>
I've used that strategy numerous times. Depending on the query, adding
an addition key/index can sometimes reduce reporting utilization
substantially.
--
-Eric 'shubes'
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