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.
Regards, Steven.
Date: Mon, 17 Jan 2011 12:20:46 -0800
Subject: Re: Super CF or two CFs?
From: davevi...@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 <ugs...@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.
