Provided herein are techniques that may be used to dramatically increase parallism for distributed DML operations. The work of distributed DML operations are distributed in a way that avoids self-dead locks, by ensuring that, for a given data block, no more than one slave is assigned to modify a row that is wholly contained by the data block or whose head row piece is contained by the data block. Assigning slaves in this way not only allows more slaves to be assigned to modify a partition, but allows for greater flexibility in load balancing.