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From Maciej Miklas <mac.mik...@gmail.com>
Subject Re: CQL 3 and wide rows
Date Mon, 19 May 2014 20:18:14 GMT
Hi James,

Clustering is based on rows. I think that you meant not clustering columns, but compound columns.
Still all columns belong to single table and are stored within single folder on one computer.
And it looks to me (but I’am not sure) that CQL 3 driver loads all column names into memory
- which is confusing to me. From one side we have wide row, but we load whole into ram…..

My understanding of wide row is a row that supports millions of columns, or similar things
like map or set. In CLI you would generate column names (or use compound columns) to simulate
set or map,  in CQL 3 you would use some static names plus Map or Set structures, or you could
still alter table and have large number of columns. But still - I do not see Iteration, so
it looks to me that CQL 3 is limited when compared to CLI/Hector.


Regards,
Maciej

On 19 May 2014, at 17:30, James Campbell <james@breachintelligence.com> wrote:

> Maciej,
> 
> In CQL3 "wide rows" are expected to be created using clustering columns.  So while the
schema will have a relatively smaller number of named columns, the effect is a wide row. 
For example:
> 
> CREATE TABLE keyspace.widerow (
> row_key text,
> wide_row_column text,
> data_column text,
> PRIMARY KEY (row_key, wide_row_column));
> 
> Check out, for example, http://www.datastax.com/dev/blog/schema-in-cassandra-1-1.​
> 
> James
> From: Maciej Miklas <mac.miklas@gmail.com>
> Sent: Monday, May 19, 2014 11:20 AM
> To: user@cassandra.apache.org
> Subject: CQL 3 and wide rows
>  
> Hi *,
> 
> I’ve checked DataStax driver code for CQL 3, and it looks like the column names for
particular table are fully loaded into memory, it this true?
> 
> Cassandra should support wide rows, meaning tables with millions of columns. Knowing
that, I would expect kind of iterator for column names. Am I missing something here? 
> 
> 
> Regards,
> Maciej Miklas


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