Stop Routing Reads to Primary: Building Causal Consistency in Java with Postgres LSN Tokens

Summary

Stop Routing Reads to Primary: Building Causal Consistency in Java with Postgres LSN Tokens Falling back to your primary database for reads right after a mutation is a lazy architectural crutch that kills your write capacity at scale. In 2026, if you aren't using causal session tokens across your edge and read replicas, you're needlessly setting money on fire with oversized primary instances. Want to go deeper? javalld.com — machine coding interview problems with working Java code and ful...