Off the WAL: Postgres to ClickHouse Without Logical Replication
October 20–23
Level: Intermediate
Your Postgres is already shipping a WAL stream to its replicas. Logical replication asks it to duplicate that work, only slower. You keep a careful eye on slots, output plugins decoding inside the source, and seconds of lag before a committed row reaches your analytical database.
We will walk through WalShadow, an open-source engine that reads the physical WAL directly, decodes it outside the source, and writes in ClickHouse's native format. In our benchmarks, it's only ~200ms from commit to queryable, at 289k rows a second, close to the source's own rate.
