[mythtv-users] Sloooow database

Brad DerManouelian myth at dermanouelian.com
Mon Jun 9 22:50:21 UTC 2008

On Jun 9, 2008, at 11:58 AM, Tom Dexter wrote:

> On Mon, Jun 9, 2008 at 12:59 PM, Brad DerManouelian
> <myth at dermanouelian.com> wrote:
>> On Jun 9, 2008, at 9:21 AM, Kevin Kuphal wrote:
>>> The original message indicated he did this already.  My gut says the
>>> 512MB is far too little despite assertations otherwise.
>> We never got solid numbers from top to see how much swap is being  
>> used
>> (if at all). My gut says he's running transcode jobs, commercial flag
>> jobs, some other processes and he's swapping RAM which absolutely
>> kills mysql performance. RAM is cheap. Get more. :)
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> While I don't do any transcoding, I do run commflagging on my backend
> machine which has only 512MB ram.  I've never had any performance
> issues of any sort.

Yes, you have. Your database is Sloooow. Just look at the subject  
line. ;)

> One factor in this however may be the fact that I'm doing only OTA, so
> I have a really small number of channels and corresponding guide data.
> I'd imagine that's a factor for at least some DB activity, especially
> scheduling.

Are you downloading your listings or using EIT scanning? If you're  
constantly inserting new records into the database from EIT data, that  
would explain the db hit.

> When I built this machine I fully planned on adding ram, but after I
> got it going I never saw any reason.  I've never even seen the 'free'
> command show any significant sign of swapping actually.  Same for my
> frontend actually...even watching HD I don't see it using more than
> half of its 512MB.

With recording, watching HD, web access, commflagging and ipod  
transcoding, even I swap with 2GB of RAM:
[mythtv at mythtv ~]$ free
             total       used       free     shared    buffers      
Mem:       2075180    1726184     348996          0      12792     
-/+ buffers/cache:     590180    1485000
Swap:      2031608    1037356     994252

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