What is ##?

geometry regression test:


QUERY: SELECT '' AS thirty, p.f1, l.s, p.f1 ## l.s AS closest
   FROM LSEG_TBL l, POINT_TBL p;
thirty|f1        |s                            |closest

------+----------+-----------------------------+--------------------------------
----
      |(0,0)     |[(1,2),(3,4)]                |(1,2)

      |(-10,0)   |[(1,2),(3,4)]                |(1,2)

      |(-3,4)    |[(1,2),(3,4)]                |(1,2)

      |(5.1,34.5)|[(1,2),(3,4)]                |(3,4)

      |(-5,-12)  |[(1,2),(3,4)]                |(1,2)

      |(10,10)   |[(1,2),(3,4)]                |(3,4)

      |(0,0)     |[(0,0),(6,6)]                |(-0,0)

This last line, in the current results, provides a value of (0,0) for
closest, but I can't find what ## means in order to determine if this is
as expected...


Marc G. Fournier
Systems Administrator @ hub.org
primary: scrappy@hub.org           secondary: scrappy@{freebsd|postgresql}.org