Google's monolithic repository provides a common source of truth for tens of
thousands of developers around the world. This article outlines the scale of
Google’s codebase, describes Google’s custom-built monolithic source repository,
and discusses the reasons behind choosing this model. We provide background on the
systems and workflows that make managing and working productively with a large
repository feasible. We also review the advantages and trade-offs of this model of
source code management.