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From Mohammed Guller <moham...@glassbeam.com>
Subject RE: Number of columns per row for composite columns?
Date Wed, 13 Aug 2014 20:50:40 GMT
4


Mohammed

From: hlqv [mailto:hlqvuong@gmail.com]
Sent: Tuesday, August 12, 2014 11:44 PM
To: user@cassandra.apache.org
Subject: Re: Number of columns per row for composite columns?

For more specifically, I declared a column family

create column family Column_Family
        with key_validation_class = UTF8Type
        and comparator = 'CompositeType(LongType,UTF8Type)'
        and default_validation_class = UTF8Type;
Number of columns will depend on only first column name in composite column or both.
For example,
With row key  = 1, I have data
1 | 20140813, user1 | value1
1 | 20140813, user2 | value2
1 | 20140814, user1 | value3
1 | 20140814, user2 | value4
(1: rowkey, "20140813, user1": composite column, "value1" : the value of column)

So the number of columns of row key 1 will be 2 or 4? (2 for 20140813 and 20140814, 4 for
each distinct composite column)
Thank you so much

On 13 August 2014 03:18, Jack Krupansky <jack@basetechnology.com<mailto:jack@basetechnology.com>>
wrote:
Your question is a little too tangled for me... Are you asking about rows in a partition (some
people call that a “storage row”) or columns per row? The latter is simply the number
of columns that you have declared in your table.

The total number of columns – or more properly, “cells” – in a partition would be
the number of rows you have inserted in that partition times the number of columns you have
declared in the table.

If you need to review the terminology:
http://www.datastax.com/dev/blog/does-cql-support-dynamic-columns-wide-rows

-- Jack Krupansky

From: hlqv<mailto:hlqvuong@gmail.com>
Sent: Tuesday, August 12, 2014 1:13 PM
To: user@cassandra.apache.org<mailto:user@cassandra.apache.org>
Subject: Number of columns per row for composite columns?

Hi everyone,
I'm confused with number of columns in a row of Cassandra, as far as I know there is 2 billions
columns per row. Like that if I have a composite column name in each row, for ex: (timestamp,
userid), then number of columns per row is the number of distinct 'timestamp' or each distinct
'timestamp, userid' is a column?

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