Loki 2.3 introduces the pattern parser. Patterns are way simpler to write than Regex. As an added bonus, it's an order of magnitudes faster than the Loki regex parser. This means that you can now query way more semi-structured logs (nginx/envoy/syslog and more) in less time than before.

https://grafana.com/blog/2021/08/09/new-in-loki-2.3-logql-pattern-parser-makes-it-easier-to-extract-data-from-unstructured-logs/