Introduction
ClickHouse is a columnar OLAP database. It runs aggregate queries across billions of rows in seconds. MySQL is what most apps run on for transactional reads and writes. Different jobs, different storage shapes, which is why people end up running them side by side: MySQL for the app, ClickHouse for analytics on top of the app's data.
The piece in the middle, the bit that copies tables from MySQL into ClickHouse and keeps them current, is what Sling does.
This guide replicates a MySQL schema into ClickHouse with Sling, in both full-refresh and incremental modes. The CLI output, row counts, and timings below all come from an actual run against a Docker MySQL on the source side and a self-hosted ClickHouse 25.4 on the target side. The same configuration works against ClickHouse Cloud; only the connection URL changes.
Installing Sling
