Every column will be retrieved (that's populated) from disk and the
requested column will then be sliced out in memory and sent back.
On 21 May 2018 at 08:34, sujeet jog <sujeet....@gmail.com> wrote:
> Folks,
>
> consider a table with 100 metrics with (id , timestamp ) as key,
> if one wants to do a selective metric read
>
> select m1 from table where id = 10 and timestamp >= '2017-01-02
> :00:00:00'
> and timestamp <= '2017-01-02 04:00:00'
>
> does the read on the specific node happen first bringing all the metrics
> m1 - m100 and then the metric is sliced in memory and retrieve , or the
> disk read happens only on the sliced data m1 without bringing m1- m100 ?
>
> here partition & clustering key is provided in the query, the question is
> more towards efficiency operation on this schema for read.
>
> create table {
> id : Int,.
> timestamp : timestamp ,
> m1 : Int,
> m2 : Int,
> m3 Int,
> m4 Int,
> ..
> ..
> m100 : Int
>
> Primary Key ( id, timestamp )
> }
>
> Thanks
>
