[PostGIS] #6034: Missing node when adding overlapping line

[PostGIS]

#6034: Missing node when adding overlapping line
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  Reporter:  Lars Aksel Opsahl  |      Owner:  strk
      Type:  defect             |     Status:  new
  Priority:  medium             |  Milestone:
 Component:  topology           |    Version:  3.6.x
Resolution:                     |   Keywords:
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Comment (by Lars Aksel Opsahl):

 Replying to [comment:8 strk]:
 > The rationale for the result being order-dependent is that by design we
 aim at keeping the existing topology as immutable as possible. The only
 reason why the existing topology changes is the limited space in which
 coordinates can be represented (floating point grid).
 >
 > What the mentioned PR does is using a controlled coordinate grid, but
 can only work if that grid is retained for all topology operations, so
 would require disabling the ability to pass a "tolerance" to topology
 population functions.
 >
 > An alternative implementation would be to support snapping incoming
 vertices to existing edges. That would still require slightly changing the
 existing topology, but at least we would reduce such change. The outcome
 would still be order dependent, in that you'd get the resulting node
 closer to the FIRST geometry that enters the topology.

 Makes sense and the result where 2 edges covers the same "space" would be
 solved. If the  movement is less than the tolerance used it should not
 cause any problems for lines that should be connected to the line that is
 slightly moved.

 If easy to implement, maybe we should test it see how it works ?
-- 
Ticket URL: <https://trac.osgeo.org/postgis/ticket/6034#comment:9>
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