[postgis-tickets] [PostGIS] #5548: ValidateTopology, failes with ERROR: XX000: GetRingEdges: edge id cannot be null

[PostGIS]

#5548: ValidateTopology, failes with ERROR:  XX000: GetRingEdges: edge id cannot
be null
--------------------------------+---------------------------
  Reporter:  Lars Aksel Opsahl  |      Owner:  strk
      Type:  defect             |     Status:  new
  Priority:  medium             |  Milestone:  PostGIS 3.4.1
 Component:  topology           |    Version:  3.4.x
Resolution:                     |   Keywords:
--------------------------------+---------------------------
Comment (by strk):

 I got access to the database exposing the problem.
 The offending query is from the step in which shells of all faces are
 constructed

 > NOTICE: Constructing geometry of all faces

 In particular, this is the dynamic SQL being executed:
 {{{
       WITH
       outside_point AS (
         SELECT ST_Translate(
           ST_StartPoint( ST_BoundingDiagonal(mbr) ),
           -1,
           -1
         )
         FROM topo.face
         WHERE face_id = $1
       ),
       leftmost_edge AS (
         SELECT
           CASE WHEN left_face = $1
           THEN
             edge_id
           ELSE
             -edge_id
           END ring_id
         FROM topo.edge
         WHERE left_face = $1 or right_face = $1
         ORDER BY
           geom <-> $2
         LIMIT 1
       ),
       edgering AS (
         SELECT *
         FROM
           GetRingEdges(
             'topo',
             (SELECT ring_id FROM leftmost_edge)
           )
       )
       SELECT
         ST_MakeLine(
           CASE WHEN r.edge > 0 THEN
             e.geom
           ELSE
             ST_Reverse(e.geom)
           END
           ORDER BY r.sequence
         ) outerRing
       FROM edgering r, topo.edge e
       WHERE e.edge_id = abs(r.edge)
 }}}

 The GetRingEdges function evidently receives a NULL, so `SELECT ring_id
 FROM leftmost_edge` returns NULL. The leftmost_edge CTE is:
 {{{
         SELECT
           CASE WHEN left_face = $1
           THEN
             edge_id
           ELSE
             -edge_id
           END ring_id
         FROM topo.edge
         WHERE left_face = $1 or right_face = $1
         ORDER BY
           geom <-> $2
         LIMIT 1
 }}}

 Getting a NULL from that query suggests that the face with id=$1 has no
 edges.
 I'm digging further.
-- 
Ticket URL: <https://trac.osgeo.org/postgis/ticket/5548#comment:2>
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