On Fri, Nov 12, 2010 at 06:06, Darren Duncan <darren@darrenduncan.net> wrote:
> This is one place that SQL made things more complicated than they needed to
> be. Multisets have generally the same structure *and* operators (union,
> etc) as tables, but they use different syntax for each. A better design
> would be to make tables and multisets interchangeable. Its an unnecessary
> distinction.
We can use unnest() to convert MULTISET into TABLE, and collect() agg
function from TABLE to MULTISET. I don't think they need to have the
same on-disk structure; they can share operators and constructor syntax
even now.
--
Itagaki Takahiro