Hello Akash, Depends what you mean by downsampling: for example if you have time as clustering key in your table you can order data DESC inside partitions and then just do a select with per partition limit ( last 10 entries in each partition for example). But if you would like to extract a totally random subset of data from an existing table (which would correspond more to downsampling) - then you need to do this in an analytical layer on top of Cassandra ( like Apache Spark). As far as I know you cannot do this in Cassandra.
Valentina On Fri, Feb 23, 2018 at 9:44 PM, Akash Gangil <akashg1...@gmail.com> wrote: > Hi Valentina, > > In that case, are there any well defined ways on how to do downsampling of > data in C*? > > thanks! > > > On Fri, Feb 23, 2018 at 11:36 AM, Valentina Crisan < > valentina.cri...@gmail.com> wrote: > >> Hello, >> >> as far as I know it is not intended for MV's to have a different TTL than >> the base tables. There was patch released at some point to not allow TTL >> setting on MV (https://issues.apache.org/jira/browse/CASSANDRA-12868). >> MV's should inherit the TTL of the base table. >> >> Valentina >> >> On Fri, Feb 23, 2018 at 6:42 PM, Akash Gangil <akashg1...@gmail.com> >> wrote: >> >>> Hi, >>> >>> I had a couple of questions: >>> >>> 1. Can I create a materialized view on a table with a TTL longer than >>> the base table? For ex: my materialized view TTL is 1 month while my base >>> table TTL is 1 week. >>> >>> 2. In the above scenario, since the data in my base table would be gone >>> after a week, would it impact data in the materialized view? >>> >>> My use case if I have some time series data, which is stored in the base >>> table by_minute and I want to downsample it to by_month. So my base table >>> stores by_minute data but my materialized view stores stores by_week data. >>> >>> thanks! >>> >>> -- >>> Akash >>> >> >> > > > -- > Akash >
