CRDTs and Rich CRDTs for Maintaining Database Integrity

CRDTs are conflict-free, replicated data types that handle concurrent updates and converge on the same state. They are crucial for building a sync layer but alone cannot maintain database integrity guarantees. Rich CRDT techniques, like compensations, build on CRDTs to preserve integrity such as referential integrity in relational databases. These techniques ensure that conflicting operations do not violate data integrity, like maintaining referential integrity when synchronizing between different databases.