linhr opened a new issue, #21955: URL: https://github.com/apache/datafusion/issues/21955
`ScalarUDFImpl::preimage` allows defining "preimage" (range of input values) for function outputs, which can be used to rewrite binary comparison expressions. The rewrite rules for equality (`=`) or inequality (`!=`) seem intuitive. But `f(x) <= c` would also be rewritten to `x < u` where `u` is the (exclusive) upper bound. I'm not sure if this holds in general. Does this assume that the function must be monotonically non-decreasing? I was trying to see if the documentation mentions monotonicity for scalar UDFs but I couldn't find it. Let me know if I misunderstood anything! -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
