Thanks for the great article with technical details! It would be interesting to know which particular queries were used during performance testing.

Also, did you try other open-source solutions for log storage and querying such as VictoriaLogs (https://docs.victoriametrics.com/VictoriaLogs/)? It should perform typical queries over logs at much faster speed than Loki (up to 1000x faster). It also supports logs with high-cardinality fields, contrary to Grafana Loki. And it can be integrated with Promtail - https://docs.victoriametrics.com/VictoriaLogs/data-ingestion/Promtail.html