" Using the post's example, consider the query of "get all readings for
sensor 1". With dynamic columns, the query is just "select * from data
where sensor_id=1". In CQL, not only does this take N different queries
(one per sample) but you have to explicitly know the collected_at values to
query for. Right?"
This does work in CQL (v3.1.1 , tried on Cassandra 2.0.4)
cqlsh:playlist> CREATE TABLE data (
... sensor_id int,
... collected_at timestamp,
... volts float,
... PRIMARY KEY (sensor_id, collected_at)
... ) WITH COMPACT STORAGE;
cqlsh:playlist> insert into data(sensor_id,collected_at,volts) values
(1,'2014-0
5-01 00:00:00',1.2);
cqlsh:playlist> insert into data(sensor_id,collected_at,volts) values
(1,'2014-0
5-02 00:00:00',1.3);
cqlsh:playlist> insert into data(sensor_id,collected_at,volts) values
(1,'2014-0
5-03 00:00:00',1.4);
cqlsh:playlist> insert into data(sensor_id,collected_at,volts) values
(2,'2014-0
5-03 00:00:00',2.4);
cqlsh:playlist> select * from data;
sensor_id | collected_at | volts
-----------+------------------------------------------+-------
1 | 2014-05-01 00:00:00Pacific Daylight Time | 1.2
1 | 2014-05-02 00:00:00Pacific Daylight Time | 1.3
1 | 2014-05-03 00:00:00Pacific Daylight Time | 1.4
2 | 2014-05-03 00:00:00Pacific Daylight Time | 2.4
(4 rows)
cqlsh:playlist> select * from data where sensor_id=1;
sensor_id | collected_at | volts
-----------+------------------------------------------+-------
1 | 2014-05-01 00:00:00Pacific Daylight Time | 1.2
1 | 2014-05-02 00:00:00Pacific Daylight Time | 1.3
1 | 2014-05-03 00:00:00Pacific Daylight Time | 1.4
(3 rows)
cqlsh:playlist>
On Tue, Aug 26, 2014 at 12:33 PM, Ian Rose <ianr...@fullstory.com> wrote:
> Unfortunately, no. I've read that and the solution presented only works
> in limited scenarios. Using the post's example, consider the query of "get
> all readings for sensor 1". With dynamic columns, the query is just
> "select * from data where sensor_id=1". In CQL, not only does this take N
> different queries (one per sample) but you have to explicitly know the
> collected_at values to query for. Right?
>
> The other suggestion, to use collections (such as a map), again works in
> some circumstances, but not all. In particular, each item in a collection
> is limited to 64k bytes which is not something we want to be limited to (we
> are storing byte arrays that occasionally exceed this size).
>
>
>
> On Tue, Aug 26, 2014 at 3:14 PM, Shane Hansen <shanemhan...@gmail.com>
> wrote:
>
>> Does this answer your question Ian?
>>
>> http://www.datastax.com/dev/blog/does-cql-support-dynamic-columns-wide-rows
>>
>>
>>
>> On Tue, Aug 26, 2014 at 1:12 PM, Ian Rose <ianr...@fullstory.com> wrote:
>>
>>> Is it possible in CQL to create a table that supports dynamic column
>>> names? I am using C* v2.0.9, which I assume implies CQL version 3.
>>>
>>> This page appears to show that this was supported in CQL 2 with the
>>> 'with comparator' and 'with default_validation' options but that CQL 3 does
>>> not support this: http://www.datastax.com/dev/blog/whats-new-in-cql-3-0
>>>
>>> Am I understanding that right? If so, what is my best course of action?
>>> Create the table using the cassandra-cli tool?
>>>
>>> Thanks,
>>> - Ian
>>>
>>>
>>
>
