Deepak - Yes, you are indeed right. I must admit I am still trying to learn what queries can and cannot be performed in Cassandra and I didn't realize that you could query on a non-fully-specified primary key, as long as you *do* fully qualify the partition key.
Cheers, Ian On Wed, Aug 27, 2014 at 11:31 AM, Deepak Shetty <shet...@gmail.com> wrote: > " 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 >>>> >>>> >>> >> >
