The is the RFC for AvocadoDB's query language. AvocadoDB is an open source nosql database (see www.avocadodb.org) offering a mixture of data models like key value pairs, documents and graphs.
The REST API for AvocadoDB is already available and stable and people are writing APIs using it. Awesome. As AvocacoDB offers more complex data structures like graphs and lists REST is not enough. We implemented a first version of a query language some time ago which is very similar to SQL and UNQL.
Then we realized that this approach was not completely satisfying as some queries cannot expressed very well with it, especially multi-valued attributes/lists. UNQL addresses this partly, but does not go far enough. Another issue are graphs. AvocadoDB supports querying graphs, neither SQL nor UNQL offer any "natural" graph traversal facilities.
As we did not find any existing query language that addresses the problems we found we had to define a new query language which is presented in the presentation.
Have some feedback on this? Come to www.avocadodb.org and tell us what you think about it. :-)