> > I still think the query language is a good idea but I have one > negative point about it. > > One of the selling point about a simple data model and access language > was that there were never issues where a query planner "refused" to do > the query the "optimal way" the user desired. For example a query > using order and limit would first order the dataset and then limit > when the user wanted to limit then order.
This would be a limitation of the expressiveness of the grammar or a failure on the part of the user and not really a problem with the query planner. The QL statements so far are simple enough that there is basically One Way to perform the operation once they are on the server. I don't see ambiguity seeping in, but I suppose this is possible. > Also without sounding syndical, I see SQL-ify catering to the lower > half. Take projecting columns from a row for example. SQL-ish is going > to encourage people to NOT learn about SlicePredicate and attempt get > by using the SQL interface. They will not understand how to take > advantage of the data model and what it provides. With 7.0 where > schema changes can happen on the fly, users are going to have more > freedom to create ColumnFamilies. Aided by their QL interface and > their pre-disposition to think SQL they are going to structure column > families like SQL tables. They could end up with unoptimized tables > and planner making the non optimal queries. > > I somewhat feel a QL language would be like Cassandra training wheels. Valid concern, but a different debate. I think we've all seen the effects of the "I did crap wrong, therefore Cassanda sucks" blog posts. I hope that Cassandra's signal can make it to the point where it is established enough to where those posts don't contribute as much noise as they currently do. Looking out a year or so into the future, I think we'll be there. At that point, features like a QL will help to make Cassandra more approachable. But whether or not Cassandra should be more approachable, I think, is a different debate. Gary.
