Thanks for the review!

Depending on how you use properties.

The following is not valid ClickHouse SQL:

select coalesce('not properties', null) as properties, coalesce(properties, events.properties) as `what is this` from events

For some reason columns in a row can't refer to previous ones. You need to use WITH for such magic.

If you alias a column as properties inside a subquery and access it from within a context where you can access it (it's basically in a join), then we'll either add or not add the alias of the subquery, depending on whether it has one or not.

That doesn't sound 100% right. For example, this is valid:

SELECT JSONExtractRaw(events.properties, '$os') as properties, upper(properties) as props, lower(events.properties) from events LIMIT 1

and the upper(properties) is not referring to events.properties, but prepending events here will fail?

(also curious why your example fails, not sure why 🤔 )

I think it's a coalesce weirdness, if I reverse the ordering in the second coalesce, it passes. I'm guessing something to do with the restriction on arguments:

Odd stuff. This query however works fine in both hogql and clickhouse:

🤷

Looks like we're good then 🤷 😅