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From Gary Dusbabek <>
Subject Re: Calling all library maintainers
Date Fri, 05 Nov 2010 15:40:37 GMT
> 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

> 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.


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