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From Jonathan Haddad <...@jonhaddad.com>
Subject Re: Tune cache MB settings per table.
Date Sun, 01 Jun 2014 23:37:08 GMT
I think of all the areas you could spend your time, this will have the
least returns.  The OS will keep the most frequently used data in memory.
 There's no reason to require cassandra to do it.

If you're curious as to what's been loaded into ram, try Al Tobey's pcstat
utility.  https://github.com/tobert/pcstat


On Sun, Jun 1, 2014 at 4:30 PM, Colin <colpclark@gmail.com> wrote:

> Have you been unable to achieve your SLA's using Cassandra out of the box
> so far?
>
> Based upon my experience, trying to tune Cassandra before the app is done
> and without simulating real world load patterns, you might actually be
> doing yourself a disservice.
>
> --
> Colin
> 320-221-9531
>
>
> On Jun 1, 2014, at 6:08 PM, Kevin Burton <burton@spinn3r.com> wrote:
>
> Not in our experience… We've been using fadvise don't need to purge pages
> that aren't necessary any longer.
>
> Of course YMMV based on your usage.  I tend to like to control everything
> explicitly instead of having magic.
>
> That's worked out very well for us in the past so it would be nice to
> still have this on cassandra.
>
>
> On Sun, Jun 1, 2014 at 12:53 PM, Colin <colin@clark.ws> wrote:
>
>> The OS should handle this really well as long as your on v3 linux
>> kernel....
>>
>> --
>> *Colin Clark*
>> +1-320-221-9531
>>
>>
>> On Jun 1, 2014, at 2:49 PM, Kevin Burton <burton@spinn3r.com> wrote:
>>
>> It's possible to set caching to:
>>
>> all, keys_only, rows_only, or none
>>
>> .. for a given table.
>>
>> But we have one table which is MASSIVE and we only need the most recent
>> 4-8 hours in memory.
>>
>> Anything older than that can go to disk as the queries there are very
>> rare.
>>
>> … but I don't think cassandra can do this (which is a shame).
>>
>> Another option is to partition our tables per hour… then tell the older
>> tables to cache 'none'…
>>
>> I hate this option though.  A smarter mechanism would be to have a
>> compaction strategy that created an SSTable for every hour and then had
>> custom caching settings for that table.
>>
>> The additional upside for this is that TTLs would just drop the older
>> data in the compactor..
>>
>> --
>>
>> Founder/CEO Spinn3r.com
>> Location: *San Francisco, CA*
>> Skype: *burtonator*
>> blog: http://burtonator.wordpress.com
>> … or check out my Google+ profile
>> <https://plus.google.com/102718274791889610666/posts>
>> <http://spinn3r.com>
>> War is peace. Freedom is slavery. Ignorance is strength. Corporations are
>> people.
>>
>>
>
>
> --
>
> Founder/CEO Spinn3r.com
> Location: *San Francisco, CA*
> Skype: *burtonator*
> blog: http://burtonator.wordpress.com
> … or check out my Google+ profile
> <https://plus.google.com/102718274791889610666/posts>
> <http://spinn3r.com>
> War is peace. Freedom is slavery. Ignorance is strength. Corporations are
> people.
>
>


-- 
Jon Haddad
http://www.rustyrazorblade.com
skype: rustyrazorblade

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