We had a workshop in Stockholm in early March to discuss what can be done to innovate MySQL in a number of areas. Most of the work here will not be useful code in yet a year or two and a lot longer before it'll be used in Enterprise Ready binaries. Obviously there is no guarantee that this early work will reach production binaries. This work is part of an aim at advancing the MySQL Architecture in the next few years.
One interesting topic we discussed was Pushdown of Query Fragments to Storage Engine.
A Query Fragment is a piece of an SQL query, for example in a 3-way join any join of 2 tables in this query is a Query Fragment, also the full query is a Query Fragment. As part of this interface the storage engine can decide to perform its own optimising using a new interface or it could rely on the MySQL Server to handle this optimisation. If the Storage Engine decides it can handle the Query Fragment and the optimiser decides to use this Query Fragment then the execution of this Query Fragment will be executed using the traditional Storage Engine API as if the Query Fragment was a normal table.
There are many engines that could make use of this new interface. Another interesting use of this interface is to implement parallel query support for the MySQL Server using this new interface. We hope to build a prototype of this sometime this year.
Please provide comments on this development on this blog, the development is in such an early phase that input is very welcome.