[PostGIS] #6017: copytopology creates blank feature_column sometimes

[PostGIS]

#6017: copytopology creates blank feature_column sometimes
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  Reporter:  robe      |      Owner:  strk
      Type:  defect    |     Status:  new
  Priority:  medium    |  Milestone:  PostGIS 3.5.5
 Component:  topology  |    Version:  3.5.x
Resolution:            |   Keywords:
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Comment (by strk):

 That's actually expected, as CopyTopology does NOT copy the layer data, so
 what you are left with is so-called "DETACHED" layers, as reported by
 TopologySummary:
 {{{
 =# select topologysummary(name) from topology where name =
 'upgrade_test_copy';
                     topologysummary
 --------------------------------------------------------
  Topology upgrade_test_copy (id 3, SRID 0, precision 0)+
  2 nodes, 1 edges, 0 faces, 1 topogeoms in 1 layers    +
  Layer 1, type Lineal (2), 1 topogeoms                 +
   Deploy: NONE (detached)                              +

 (1 row)
 }}}

 Since there's no "deploy" target for those layers (that are known to exist
 as the relation table data IS copied and refers to them) the code write
 arbitrary information in the "schema_name", "table_name" and
 "feature_column" of the newly created layer record; and when I implemented
 that I evidently went with the topology schema as the detached/phantom
 layer's "schema_name", the literal "LAYER#" as the "table_name" and a
 plain NULL as the "feature_column". And one of these values (I guess the
 NULL) is what TopologySummary recognizes as a signe of a "DETACHED" layer.

 I hope this is clear and see #1195 for a past discussion about this
 situation and proposals for improving them.

 But given the above, this ticket should probably be closed as invalid
 (expected). Just make sure it's "always" and not "sometimes' that this
 happen, maybe ?
-- 
Ticket URL: <https://trac.osgeo.org/postgis/ticket/6017#comment:2>
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