Query ClickHouse over HTTP with readonly=1 on every request

Why HTTP

ClickHouse ships a full HTTP interface on port 8123 (8443 for HTTPS). Using it means DevOpsPad works with self-hosted servers and ClickHouse Cloud alike, through ordinary TLS, and through SSH tunnels without any special driver.

Each request is sent with readonly=1, max_result_rows=500 with result_overflow_mode=break, and max_execution_time=15. These are enforced by the server, not just by the app: ClickHouse refuses writes, stops reading after 500 rows and cancels long scans. The app adds its own 20-second outer timeout on top.

Browse before you scan

Pick a database to list its tables. Opening a table shows its column types, its data skipping indexes from system.data_skipping_indices, and the DDL from SHOW CREATE TABLE, so you can see the ORDER BY key and partitioning before you write a query that scans the whole table.

SELECT toStartOfHour(ts) AS hour, count() AS events
FROM analytics.events
WHERE ts >= now() - INTERVAL 1 DAY
GROUP BY hour
ORDER BY hour;

Each query tab keeps its own database scope, and results can be sorted, filtered and exported to CSV.

ClickHouse Cloud and private servers

For ClickHouse Cloud, use port 8443 and enable Use TLS with certificate verification. For a server inside a private network, turn on an SSH tunnel and keep the host as it is seen from the SSH server.

Limits

The native protocol and mutations are not supported. Results are previews for investigation, not exports of full tables. See result limits for how the caps work across engines, or the MySQL connector for transactional databases.