# Introducing WalShadow: Sub-second Postgres replication to ClickHouse from physical WAL

DevFeed: [Introducing WalShadow: Sub-second Postgres replication to ClickHouse from physical WAL](<https://devfeed.tech/articles/introducing-walshadow-sub-second-postgres-replication-to-clickhouse-from-physical-wal-5344.md>)

Original publisher: [Read original article](<https://clickhouse.com/blog/introducing-walshadow>)

Author: Sai Srirampur

Published: 2026-09-10T15:53:42Z

Content type: article

Language: en

Sources: [ClickHouse Blog](<https://devfeed.tech/sources/clickhouse-blog.md>)

Topics: [clickhouse](<https://devfeed.tech/topics/clickhouse.md>), [Database](<https://devfeed.tech/topics/database.md>), [schema-evolution](<https://devfeed.tech/topics/schema-evolution.md>), [Latency](<https://devfeed.tech/topics/latency.md>)

Tags: [analytics](<https://devfeed.tech/tags/analytics.md>), [architecture](<https://devfeed.tech/tags/architecture.md>), [benchmarks](<https://devfeed.tech/tags/benchmarks.md>), [clickhouse](<https://devfeed.tech/tags/clickhouse.md>), [github](<https://devfeed.tech/tags/github.md>), [latency](<https://devfeed.tech/tags/latency.md>), [open-source](<https://devfeed.tech/tags/open-source.md>), [postgres](<https://devfeed.tech/tags/postgres.md>), [replication](<https://devfeed.tech/tags/replication.md>), [schema-evolution](<https://devfeed.tech/tags/schema-evolution.md>), [transactions](<https://devfeed.tech/tags/transactions.md>)

## AI overview

WalShadow is an open-source engine that replicates PostgreSQL data to ClickHouse from the physical WAL stream. The article describes benchmark results of about 200 ms visibility latency and 289K rows per second, plus support for initial loads, continuous replication, schema evolution, recovery, and source switchovers.

## Source excerpt

WalShadow replicates Postgres data directly from physical WAL into ClickHouse, delivering around 200 ms latency and 289,000 rows per second in benchmarks.