Transaction select and selectAndProcess

[dportabella]

Transaction.select
/**
* Returns all records returned by the query after being converted by the
* given block. All objects are kept in memory to this method is no suited
* for very big result sets. Use selectAndProcess if you need to process
* bigger datasets.
...
*/

I've a big resultset, and I get a OutOfMemoryException with Transaction.select.
I've solved it using selectAndProcess instead of select.

However, why does select have this limitation?
why does it keep all the rows in memory?
couldn't it return an iterator, instead of a sequence, and call the block when the iterator requires it?