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From Ian Holsman <had...@holsman.net>
Subject Re: need some help with counters
Date Fri, 10 Jun 2011 12:36:15 GMT

On Jun 9, 2011, at 10:04 PM, aaron morton wrote:

> I may be missing something but could you use a column for each of the last 48 hours all
in the same row for a url ?
> 
> e.g. 
> {
> 	"/url.com/hourly" : {
> 		"20110609T01:00:00" : 456,
> 		"20110609T02:00:00" : 4567,
> 	}
> }

yes.. that would work better... I was storing all the different times in the same row.
{
 	"/url.com" : {
	 "H-20110609T01:00:00" : 456,
	 "H-0110609T02:00:00" : 4567,
	 "D-0110609" : 5678,
	}
}

I am wondering how to index on the most recent hour as well. (ie show me top 5 URLs type query)..


> 
> Increment the current hour only. Delete the older columns either when a read detects
there are old values or as a maintenance job. Or as part of writing values for the first 5
minutes of any hour. 

yes.. I thought of that. The problem with doing it on read is there may be a case where a
old URL never gets read.. so it will just sit there taking up space.. the maintenance job
is the route I went down.

> 
> The row will get spread out over a lot of sstables which may reduce read speed. If this
is a problem consider a separate CF with more aggressive GC and compaction settings. 

Thanks!
> 
> Cheers
> 
> 
> -----------------
> Aaron Morton
> Freelance Cassandra Developer
> @aaronmorton
> http://www.thelastpickle.com
> 
> On 10 Jun 2011, at 09:28, Ian Holsman wrote:
> 
>> So would doing something like storing it in reverse (so I know what to delete) work?
Or is storing a million columns in a supercolumn impossible. 
>> 
>> I could always use a logfile and run the archiver off that as a worst case I guess.

>> Would doing so many deletes screw up the db/cause other problems?
>> 
>> ---
>> Ian Holsman - 703 879-3128
>> 
>> I saw the angel in the marble and carved until I set him free -- Michelangelo
>> 
>> On 09/06/2011, at 4:22 PM, Ryan King <ryan@twitter.com> wrote:
>> 
>>> On Thu, Jun 9, 2011 at 1:06 PM, Ian Holsman <hadoop@holsman.net> wrote:
>>>> Hi Ryan.
>>>> you wouldn't have your version of cassandra up on github would you??
>>> 
>>> No, and the patch isn't in our version yet either. We're still working on it.
>>> 
>>> -ryan
> 


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