[postgis-tickets] [PostGIS] #3975: ST_Transform references spatial_ref_sys without schema

[PostGIS]

#3975: ST_Transform references spatial_ref_sys without schema
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  Reporter:  javitonino  |      Owner:  pramsey
      Type:  defect      |     Status:  new
  Priority:  medium      |  Milestone:  PostGIS 2.4.3
 Component:  postgis     |    Version:  2.4.x
Resolution:              |   Keywords:
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Comment (by pramsey):

 OK, I can see two fixes right now, both equally ugly in their own way.

 Fix #1:

 * Change `st_transform` and `postgis_transform_geometry` into SQL wrappers
 move the actual C bindings into `_st_transform` and
 `_postgis_transform_geometry`.
 * In the wrappers, call the C bindings but include @extschema@ as an
 argument, so that we inject the schema into the C call.
 * Potentially cleaner but still ugly variant: change the signature of
 `st_transform` and `postgis_transform_geometry` to have an extra 'schema'
 parameter that has a default value of @extschema@, then we can avoid the
 extra level of indirection and get the install schema injected still.
 Depends on defaults working and involves changing signature of existing
 heavily used function.

 Fix #2:

 * Go into the C guts of `st_transform` and `postgis_transform_geometry`.
 * The FunctionCallInfo includes the Oid of the function being called.
 * In the PgSQL syscache, look up the namespace that is associated with
 that function Oid.

 Both fix #1 and #2 will require changing a lot of proj lookup code to take
 not just the SRID number being looked up, but also the schema to look for
 spatial_ref_sys in.

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Ticket URL: <https://trac.osgeo.org/postgis/ticket/3975#comment:2>
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