> I noticed that the regression test results don't include the following case: > > select string_agg(a) from (values(null),(null)) g(a); > > There is one similar where a delimiter is provided. > > Which leads me to ask for clarification, would it be safe to assume that > string_agg can never itself return null?
if all values are null, then result is null.
Pavel
Ah, I was looking at the expected results, and couldn't see a NULL outcome, but then these aren't indicated in such results anyway.
