crate/crate — pull request #1399 by seut (2014-11-25 17:25:58+00:00)
Title: Add sql query circuit breaker.

This adds a sql query circuit breaker which tries to estimate the amount of memory needed by a certain operation of a query to prevent a OutOfMemory exception.
It raises a CircuitBreakingException if the limit exceeded.
The default limit is 60% of the available HEAP.

The limit can be configured using the ``crate.breaker.query.limit`` and related ``crate.breaker.query.overhead`` settings.