Limit on number of columns

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Limit on number of columns

Ruebenacker, Oliver A

 

     Hello,

 

  For the limit of number of cells (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

[hidden email] | www.Altisource.com

 

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Re: Limit on number of columns

Jack Krupansky-2
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 <[hidden email]> wrote:

 

     Hello,

 

  For the limit of number of cells (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: <a href="tel:%28617%29%20728-5582" value="+16177285582" target="_blank">(617) 728-5582 | ext: 275585

[hidden email] | www.Altisource.com

 

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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.
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Re: Limit on number of columns

Robert Coli-3
In reply to this post by Ruebenacker, Oliver A
On Wed, Mar 18, 2015 at 12:43 PM, Ruebenacker, Oliver A <[hidden email]> wrote:

  For the limit of number of cells (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?


I tend to still think of this in terms of storage partitions and how many storage columns a given one may contain. It's possible that apache doc has not been updated to reflect the new language of "partitions" and "cells" and etc.

A given partition can contain 2Bn storage columns, regardless of how many other columns there are in other partitions.

=Rob