Gregory Stark <stark@enterprisedb.com> writes:
> Here's something else which confused me just now. Why does the second query
> return NULL instead of an array slice?
Because it isn't a slice expression --- you used colon nowhere, so the
result type is going to be text not text[]. (Remember that the parser
must determine the expression's result type at parse time, so whether
there are enough subscripts can't enter into this.) Our alternatives
here are to throw a subscripting error or return NULL. I'd personally
have gone with throwing an error, I think, but it seems far too late to
revisit that decision.
regards, tom lane