Hmm. Because the clustering key is (event_time, "timestamp"), event_time
must be specified as well - hopefully that info is available to the ux.
Unfortunately you will then hit another problem with your query: you are
selecting a collection field... this will not work with IN on "timestamp".
So you could select all the "timestamp"s for an asset_id/event_time:
> SELECT * from sensor_info_table where asset_id = 'a' and event_time =
> 1231234;
Or you could apply a range of "timestamp"s:
> SELECT * from sensor_info_table where asset_id = 'a' and event_time =
> 1231234 and "timestamp" > 1d934af3-3178-11e4-ba8d-406c8f1838fa and
> "timestamp" < 20b82021-3178-11e4-abc2-406c8f1838fa;
BTW the secondary indices are not a good idea: high cardinality and of no
use in this query that I can see.
ml
On Sun, Aug 31, 2014 at 8:40 PM, Subodh Nijsure <subodh.nijs...@gmail.com>
wrote:
> Not really event time stamp is created by the sensor when it reads data
> and timestamp is something server creates when inserting data into
> cassandra db. At later point in time my django ux allows users to browse
> this data and reference interesting data points via the timestamp field.
> The timestamp field is my bridge between Sal and nosql world.
>
> Subodh
> On Aug 31, 2014 5:33 PM, "Laing, Michael" <michael.la...@nytimes.com>
> wrote:
>
>> Are event_time and timestamp essentially representing the same datetime?
>>
>> On Sunday, August 31, 2014, Subodh Nijsure <subodh.nijs...@gmail.com>
>> wrote:
>>
>>> I have following database schema
>>>
>>> CREATE TABLE sensor_info_table (
>>> asset_id text,
>>> event_time timestamp,
>>> "timestamp" timeuuid,
>>> sensor_reading map<text, text>,
>>> sensor_serial_number text,
>>> sensor_type int,
>>> PRIMARY KEY ((asset_id), event_time, "timestamp")
>>> );
>>>
>>> CREATE INDEX event_time_index ON sensor_info_table (event_time);
>>>
>>> CREATE INDEX timestamp_index ON sensor_info_table ("timestamp");
>>>
>>> Now I am able to insert the data into this table, however I am unable
>>> to do following query where I want to select items with specific
>>> timeuuid values.
>>>
>>> It gives me following error.
>>>
>>> SELECT * from mydb.sensor_info_table where timestamp IN (
>>> bfdfa614-3166-11e4-a61d-b888e30f5d17 ,
>>> bf4521ac-3166-11e4-87a3-b888e30f5d17) ;
>>>
>>> Bad Request: PRIMARY KEY column "timestamp" cannot be restricted
>>> (preceding column "event_time" is either not restricted or by a non-EQ
>>> relation)
>>>
>>> What do I have to do to make this work?
>>>
>>> For what its worth I am using django for my front end development and
>>> I am using "timestamp timeuuid" field as unique indentifier to
>>> reference specific sensor reading from django framework -- since
>>> cassandra doesn't have way to generate unique id upon insert (like
>>> old-style rdms's auto-fields).
>>>
>>>
>>> Below is software version info.
>>>
>>> show VERSION ; [cqlsh 4.1.1 | Cassandra 2.0.9 | CQL spec 3.1.1 |
>>> Thrift protocol 19.39.0]
>>>
>>> I really don't understand what the error message preceeding column
>>> "event_time" is either not restricted or by no-EQ relation?
>>>
>>> -Subodh Nijsure
>>>
>>
