[postgis-tickets] [PostGIS] #5237: postgis_extensions_upgrade fails with ERROR: there is no unique or exclusion constraint matching the ON CONFLICT specification

[PostGIS]

#5237: postgis_extensions_upgrade fails with ERROR: there is no unique or
exclusion constraint matching the ON CONFLICT specification
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  Reporter:  robe     |      Owner:  pramsey
      Type:  defect   |     Status:  new
  Priority:  medium   |  Milestone:  PostGIS 3.3.2
 Component:  postgis  |    Version:  3.3.x
Resolution:           |   Keywords:
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Comment (by strk):

 I think the explanation is that someone removed the primary key on the
 spatial_ref_sys table on some databases. Wheter or not it's up to us
 to re-create that index is debatable. The database is in unexpected
 conditions (read "broken") without that primary key. Maybe what we
 can do is print a friendly error message for the user recommending to
 repair the database in order to proceed with the upgrade
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Ticket URL: <https://trac.osgeo.org/postgis/ticket/5237#comment:8>
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