It seems like you should be able to solve it with two more queries
immediately after your first query:
SELECT * FROM timeseries WHERE tstamp < ${MIN(firstQuery.tstamp)} LIMIT 1
SELECT * FROM timeseries WHERE tstamp > ${MAX(firstQuery.tstamp)} LIMIT 1
On Tue, Jan 13, 2015 at 9:31 AM, Hugo José Pinto <hugo.pi...@inovaworks.com>
wrote:
> Hi!
>
> We're using cassandra to store a time series, using a table similar to:
>
> CREATE TABLE timeseries (
> source_id uuid,
> tstamp timestamp,
> value text,
> PRIMARY KEY (source_id, tstamp)
> ) WITH CLUSTERING ORDER BY (tstamp DESC);
>
> With that, we do a ranged query with tstamp > x and tstamp < y to gather
> all events within a time window.
>
> Now, due to the variable granularity of incoming data, we have no
> guarantee that our data points are close to the requested interval. In
> order to compute derived values, we'd need the values immediately before
> and after the requested range.
>
> Any ideas on what would be the best way to approach this in Cassandra CQL?
>
> Many thanks for any help!
>
> --
> Hugo José Pinto
>
>
