Calcite’s adapter framework makes it easy to push down filters, aggregations to third-party sources, and to express more powerful and data-source-specific optimizations.
Is Drill building on Calcite’s support or doing it its own way? Calcite doesn’t have a Cassandra adapter but the same approach taken in the MongoDb, Splunk, Phoenix adapters could be used. On Jan 8, 2015, at 9:11 AM, Tomer Shiran <tshi...@gmail.com> wrote: > I think that any valid SQL statement should work with any data source. > Drill should: > > - Push down as much processing as possible into the data source > (Cassandra in this case) > - Maintain as much data locality as possible (ie, spread the work so > that each drillbit is handling local data) > - In the worst case, Drill should pull the entire table from the data > source if that's what's needed to satisfy the query. > > > On Thu, Jan 8, 2015 at 8:29 AM, Yash Sharma <yash...@gmail.com> wrote: > >> Hi Folks, >> This thread is to discuss few scenarios how Cassandra works - and how do we >> think it should be supported in Drill. >> >> While they are not supported in Cassandra inherently but its doable on >> Drill's end once we fetch a superset of data without these cases. >> >> 1. Filtering non indexed column in Cassandra >> 2. Filtering by subset of primary key >> 3. OR condition in where clause >> >> Should we apply filters at Drill's end and support these features or we >> propagate an error back to user for asking for a valid Cassandra based >> query? >> >> ----- >> Examples: >> Here 'trending_now' is a dummy table with (id, rank, pog_id) where >> (id,rank) is primary key pair. >> 1. >> cqlsh:recsys> select * from trending_now where pog_id=10004 ; >> Bad Request: No indexed columns present in by-columns clause with Equal >> operator >> >> 2. >> cqlsh:recsys> select * from trending_now where rank=4; >> Bad Request: Cannot execute this query as it might involve data filtering >> and thus may have unpredictable performance. If you want to execute this >> query despite the performance unpredictability, use ALLOW FILTERING >> P.S. ALLOW FILTERING is not permitted in Cassandra java driver as of now. >> >> 3. >> cqlsh:recsys> select * from trending_now where rank=4 or id='id0004'; >> Bad Request: line 1:40 missing EOF at 'or' >> >> 4. Valid Query: >> cqlsh:recsys> select * from trending_now where id='id0004' and rank=4; >> >> id | rank | pog_id >> --------+------+-------- >> id0004 | 4 | 10002 >> >> (1 rows) >>
