Github user fhueske commented on the issue:
https://github.com/apache/flink/pull/5638
Thanks for the PR @buptljy!
As mentioned in the comment, the function should be exposed similar to
`ln()` and `log10()` as `expr.log(base)`. For that the expression parser would
need to be adapted.
I'll do that and also update docs and tests to reflect these changes before
merging.---
