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From Robert Coli <rc...@eventbrite.com>
Subject Re: Limit on the size of a list
Date Mon, 13 May 2013 18:08:17 GMT
On Sun, May 12, 2013 at 6:26 PM, Edward Capriolo <edlinuxguru@gmail.com> wrote:
> 2 billion is the maximum theoretically limit of columns under a row. It is
> NOT the maximum limit of a CQL collection. The design of CQL collections
> currently require retrieving the entire collection on read.

Each column has a byte overhead of 15 bytes [1]. Assuming a column key
of type "int" [2] and no column value, a 2 billion column row is
approximately 35 gigabytes. This is before including the column index.
Anyone attempting to actually create and interact with a single row
containing 2 billion columns seems likely to quickly discover just how
meaningless the theoretical maximum is, so I'm not sure why we refer
to this number..

=Rob
[1] http://btoddb-cass-storage.blogspot.com/2011/07/column-overhead-and-sizing-every-column.html
[2] The minimum size to actually have 2Bn unique column keys.

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