Shuyi, Just wanted to check in and see how things were going in terms of putting together a PR with this. Let me know if there's any way I can help!
Cheers, -- Michael Mior michael.m...@gmail.com 2016-08-04 3:33 GMT-04:00 Shuyi Chen <suez1...@gmail.com>: > Thanks a lot, Michael and Jordan. I got it working with the suggestion. > I'll send a pull request later for you guys to help review. > > Also, I got another question. When I run a PrepareStatement in calcite, I > also want to push down part of the PrepareStatement in CQL to cassandra. > For example, > > Assuming the cassandra table contains field: a, b, c, and a is the only > primary key. > > calcite PrepareStatement is: select a, b, c from table1 where a = ? and b > < ?; > > I want to push down CQL PrepareStatement: select a, b, c from table1 where > a = ? to cassandra, and store the cassandra PrepareStatement inside the > calcite PrepareStatement. > > And when we bind the data to execute the calcite PrepareStatement, I need > to be able to retrieve the stored cassandra PrepareStatement and bind the > data for it to execute the cassandra query. > > I would love to get some advice on how to implement this. Thanks a lot. > > > > > On Wed, Aug 3, 2016 at 1:22 PM, jordan.halter...@gmail.com < > jordan.halter...@gmail.com> wrote: > > > Sure, I'm no Cassandra expert and obviously the implementation needs to > > handle whatever actually can be pushed down to C*. One should not follow > my > > advice precisely. The methods that are required to determine whether a > > predicate is supported are already present in CassandraFilterRule. I was > > just commenting on how one would go about splitting a filter based on > what > > is supported/not supported. So, replace "equality predicate" with > "whatever > > Cassandra supports" and use the existing isEqualityOnKey method. > > > > > On Aug 3, 2016, at 11:44 AM, Michael Mior <mm...@uwaterloo.ca> wrote: > > > > > > 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." > > >> > > > > > > -- > "So you have to trust that the dots will somehow connect in your future." >
