It's more complicated than that. For equality predicates, it's a matter of splitting out equality predicates involving a field and a literal. Cassandra can't handle predicates involving expressions or equality between fields. Cassandra can also handle some range predicates if the partition key is already restricted by an equality predicate and the range predicate is part o the clustering key.
Cheers, -- Michael Mior michael.m...@gmail.com 2016-08-03 14:21 GMT-04:00 jordan.halter...@gmail.com < jordan.halter...@gmail.com>: > It's just a matter of splitting out equality predicates. What I would do > is create a Filter rule that splits the filter based on whether a predicate > is an equality. If the Filter is split, the rule returns a Filter with the > equality predicates as inputs to the non-equality predicates. That should > allow the CassandraFilterRule to convert the Filter with equality > predicates and for the rest of the predicates above to be implemented in > Enumerable convention. > > You can look at the rules in core for some examples of splitting > expressions. Just ensure equality predicates are pushed down or you can > implement a rule for pushing them down past other filters. > > > On Aug 3, 2016, at 10:57 AM, Shuyi Chen <suez1...@gmail.com> wrote: > > > > Hi, > > > > I am working on improving the cassandra adapter. Right now, I found that > if > > my filter contains non-primary keys, calcite will just reject the filter > > and just execute a no-filter cql query which is bad. I am wondering how > I > > can split the filter into cassandra supported part and > > cassandra-non-supported part, and push down the cassandra supported part > to > > cql. Below is an example. > > > > Assuming the cassandra table contains field: a, b, c, and a is the only > > primary key. > > > > calcite sql is: select a, b, c from table1 where a = 'xxx' and b < 3223; > > > > I want to push down cql: select a, b, c from table1 where a = 'xxx' to > > cassandra, > > > > But right now, the cassandra adapter will only push down: select a, b, c > > from table1, which is bad for cassandra. > > > > Thanks a lot. > > Shuyi > > > > -- > > "So you have to trust that the dots will somehow connect in your future." >
