Distributed Data Consistency Patterns#

In a monolith with a single database, you get ACID transactions. In microservices, each service owns its database. Cross-service consistency requires explicit patterns because distributed ACID transactions are impractical in most real systems.

CAP Theorem: Practical Implications#

The CAP theorem states that a distributed system can provide at most two of three guarantees: Consistency, Availability, and Partition tolerance. Since network partitions are inevitable, you choose between consistency and availability during partitions.