Generally a concern for limitations on number of columns is a concern about storage for rows in a partition. Cassandra is a column-oriented database, but this is really referring to its cell-oriented storage structure, with each column name and column value pair being a single cell (except collections, which may occupy multiple cells per column, one for each value in the collection.) So, the issue is not the total number of column names used, but the total number of cells used in a partition. So, for your example, you have 20 cell values and... 20 column names.
-- Jack Krupansky On Wed, Mar 18, 2015 at 3:43 PM, Ruebenacker, Oliver A < [email protected]> wrote: > > > Hello, > > > > For the limit of number of cells > <http://wiki.apache.org/cassandra/CassandraLimitations> (columns *rows) > per partition, I wonder what we mean by number of columns, since different > rows may have different columns? Is the number of columns the number of > columns of the biggest row, or the union of all columns across all rows? > E.g. if I have two rows, one has ten columns and the other has ten > different columns, would that be considered a total of ten or twenty > columns? > > > > Thanks! > > > > Best, Oliver > > > > Oliver Ruebenacker | Solutions Architect > > > > Altisource™ > > 290 Congress St, 7th Floor | Boston, Massachusetts 02210 > > P: (617) 728-5582 | ext: 275585 > > [email protected] | www.Altisource.com > > > > > *********************************************************************************************************************** > > This email message and any attachments are intended solely for the use of > the addressee. If you are not the intended recipient, you are prohibited > from reading, disclosing, reproducing, distributing, disseminating or > otherwise using this transmission. If you have received this message in > error, please promptly notify the sender by reply email and immediately > delete this message from your system. > This message and any attachments may contain information that is > confidential, privileged or exempt from disclosure. Delivery of this > message to any person other than the intended recipient is not intended to > waive any right or privilege. Message transmission is not guaranteed to be > secure or free of software viruses. > > *********************************************************************************************************************** >
