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From Steven Mac <ugs...@hotmail.com>
Subject RE: Super CF or two CFs?
Date Mon, 17 Jan 2011 23:12:55 GMT

I guess I was maybe trying to simplify the question too much. In reality I do not have one
volatile part, but multiple ones (say all trading data of day). Each would be a supercolumn
identified by the time slot, with the individual fields as subcolumns.

Of course, I could prefix the time slot identifier to the field names and make do with a normal
CF, but couldn't this be done for any super column? In other words, why have it at all?

Steven.

> Date: Mon, 17 Jan 2011 22:58:14 +0000
> Subject: Re: Super CF or two CFs?
> From: stephen.alan.connolly@gmail.com
> To: user@cassandra.apache.org
> 
> On 17 January 2011 22:36, Steven Mac <ugsmac@hotmail.com> wrote:
> > Sure, consider stock data, where the stock symbol is the row key. The stock
> > data consists of a rather stable part and a very volatile part, both of
> > which would be a super column. The stable super column would contain
> > subcolumns such as company name, address, and some annual or quarterly data.
> > The volatile super column would contain periodic stock data, such as current
> > price, last trade times, volumes, buyers, sellers, etc.
> >
> > The volatile super columns would be updated every few minutes, many rows at
> > once using a single batch_mutate. The data would be read using a get on a
> > single row key, returning both supercolumns and all subcolumns.
> >
> > The data could also be split over two column families, one for the stable
> > part and one for the volatile part. The updates would be the same, while a
> > read would require two get operations.
> 
> I'm not seeing why you need to use supercolumns for this at all.
> 
> Standard columns would seem just fine in this case (as long as you
> have good naming for your columns)
> 
> And you probably only need one column family... but people more expert
> than me could advise better...
> 
> I guess the question I have is why you feel the solution should
> involve supercolumns
> 
> -Stephen
> 
> >
> > Regards, Steven.
> >
> > ________________________________
> > Date: Mon, 17 Jan 2011 12:20:46 -0800
> > Subject: Re: Super CF or two CFs?
> > From: daveviner@gmail.com
> > To: user@cassandra.apache.org
> >
> > can you give an example of the data and how you'd access it?
> > what would your expected columns (and/or supercolumns) be?
> >
> > Dave Viner
> > On Mon, Jan 17, 2011 at 11:05 AM, Steven Mac <ugsmac@hotmail.com> wrote:
> >
> > How can I best map an object containing two maps, one of which is updated
> > very frequently and the other only occasionally?
> >
> > a) As one super CF, which each map in a separate supercolumn and the map
> > entries being the subcolumns?
> > b) As two CFs, one for each map.
> >
> > I'd like to discuss the why behind a choice, in order to learn about the
> > impact of a design choice on performance, SStable size/disk usage,
> > compactions, etc.
> >
> > Regards, Steven.
> >
> > PS: Objects will always be read as a whole.
> >
 		 	   		  
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