A Tiny SQL Engine for JSON Streams Fits Between jq and a Stream Processing Cluster

Mon, 05 Oct 2026 00:00:00 +0000

Your service writes one JSON object per line to stdout, and you want the average cpu for host web-3 over the last five minutes. jq can’t answer that, because it forgets each object once it has printed it and has no idea what “five minutes” means. You can fake both with jq -n 'reduce inputs as $e (...)' plus a timestamp comparison, and you’ll have a script nobody wants to touch twice. DuckDB answers the question in one line, but only against a file as it exists right now. ksqlDB, Materialize, RisingWave, Arroyo and Flink SQL answer it continuously, once you’ve deployed a service and agreed to operate it.

Stream Processing on App Coding

A Tiny SQL Engine for JSON Streams Fits Between jq and a Stream Processing Cluster