On Mon, Aug 13, 2012 at 7:17 PM, Adam Mackler <AdamMackler@gmail.com> wrote:
>
> Next, uncomment the final UNION four lines from the end. When I do
> that I then get a two row result. I'm not an expert on recursive
> CTEs, but I don't believe a UNION should decrease the number of rows
> returned.
I haven't dug through all of it yet but it's definitely the case that
UNION can reduce the number of rows returned. If there are any
duplicates in one side of the union they'll be eliminated by the
UNION.
That said your input set doesn't have any duplicates so that shouldn't
be relevant. For some reason I'm getting a syntax error trying to
reproduce your problem but I have an old build of Postgres lying
around so I'm going to update and try again.
--
greg