Design patterns·Modelling the domain
you can change these five objects together in one transaction, and anything outside them has to wait its turn.
Aggregate
Also calledaggregate pattern, consistency boundary
A cluster of objects treated as one unit for changes, with a boundary that defines what must be consistent immediately. It is the pattern that decides transaction scope and lock scope, so it is a performance and concurrency decision as much as a modelling one. Making aggregates too large is the standard mistake, and it shows up as contention rather than as anything a modeller would notice.