[postgis-tickets] [PostGIS] #4858: ST_DumpPoints ring indices are inconsistent with ST_DumpRings and ST_InteriorRingN

[PostGIS]

#4858: ST_DumpPoints ring indices are inconsistent with ST_DumpRings and
ST_InteriorRingN
---------------------+---------------------------
 Reporter:  mdavis   |      Owner:  pramsey
     Type:  defect   |     Status:  new
 Priority:  medium   |  Milestone:  PostGIS 3.1.2
Component:  postgis  |    Version:  2.5.x
 Keywords:           |
---------------------+---------------------------
 `ST_DumpPoints` produces polygon ring indices which start at 1, for the
 shell, and 2 and up for holes.  This is inconsistent with `ST_DumpRings`,
 which produces index 0 for the shell, and 1 and up for holes. It is also
 inconsistent with `ST_InteriorRingN`, which numbers holes starting at 1.

 Note that `ST_InteriorRingN` uses OGC standard numbering, which is
 1-based.

 It would be good to have consistency between functions, conformity with
 the standard, and avoid arithmetic to adjust indexes.  Perhaps
 `ST_DumpPoints` should be changed to number rings starting at 0.

 For example:
 {{{
 SELECT dmp.path, ST_AsText(dmp.geom)
 FROM ST_DumpPoints('POLYGON (( 3 0, 3 3, 6 3, 6 0, 3 0 ), ( 5 1, 4 2, 5 2,
 5 1 ))':: geometry) AS dmp;

  path  | st_astext
 -------+------------
  {1,1} | POINT(3 0)
  {1,2} | POINT(3 3)
  {1,3} | POINT(6 3)
  {1,4} | POINT(6 0)
  {1,5} | POINT(3 0)
  {2,1} | POINT(5 1)
  {2,2} | POINT(4 2)
  {2,3} | POINT(5 2)
  {2,4} | POINT(5 1)
 }}}
 but:
 {{{
 SELECT dmp.path, ST_AsText(dmp.geom)
 FROM ST_DumpRings('POLYGON (( 3 0, 3 3, 6 3, 6 0, 3 0 ), ( 5 1, 4 2, 5 2,
 5 1 ))':: geometry) AS dmp;

  path |           st_astext
 ------+--------------------------------
  {0}  | POLYGON((3 0,3 3,6 3,6 0,3 0))
  {1}  | POLYGON((5 1,4 2,5 2,5 1))
 }}}

-- 
Ticket URL: <https://trac.osgeo.org/postgis/ticket/4858>
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