Setting prefetch to a value higher than 1000 triggers a recursion warning

[vijaygrk]

(node) warning: Recursive process.nextTick detected. This will break in the next version of node. Please use setImmediate for recursive deferral.

RangeError: Maximum call stack size exceeded

I am using the latest version.

[bnoordhuis]

@raymondfeng By the looks of it, lib/oracle.js should be using setImmediate(), not process.nextTick().