> The where operator will validate that the syntax is valid, but it will pass unknown function calls through to the underlying database. In RunReveal's case, we use Clickhouse under the hood, so if we wanted to do a case-insensitive match we could still use Clickhouse's lower function.

From the release blog [1] they mention that unknown functions are passed through to the underlying SQL engine -- this let's them target anything from mysql, Postgres, ClickHouse or proprietary engines like Snowflake.

1. https://blog.runreveal.com/introducing-pql/