PgDog: A Clever Postgres Proxy for Sharding

PgDog is a network proxy that intercepts all communication between Postgres clients and servers, understands SQL to infer query destinations, and requires no application code changes. It parses SQL queries, extracts sharding keys, uses Postgres's built-in partitioning hash function, and routes queries to the correct database shard. The article details how PgDog handles simple and extended protocols, cross-shard queries, and distributed COPY operations, ultimately enabling Postgres sharding and linearly scaling data ingestion speed.