Whenever I mention the limit in a talk I say, "2 Billion columns" in a faux 10 year old voice :). Cassandra can have a 2billion column row. A 60MB row in row cache will make the JVM sh*t the bed. (row cache you should not use anyway). As rcoli points out a 35 GB row, I doubt you can do anything with it that will finish in less then the rpc_timeout. In a single request I personally would not try more then 10K columns.
On Mon, May 13, 2013 at 2:08 PM, Robert Coli <rc...@eventbrite.com> wrote: > On Sun, May 12, 2013 at 6:26 PM, Edward Capriolo <edlinuxg...@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. >
