[postgis-devel] [PostGIS] #1831: ability to separate user defined spatial_ref_sys from installed

[PostGIS]

#1831: ability to separate user defined spatial_ref_sys from installed
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 Reporter:  robe     |       Owner:  pramsey      
     Type:  defect   |      Status:  new          
 Priority:  medium   |   Milestone:  PostGIS 2.1.0
Component:  postgis  |     Version:  2.0.x        
 Keywords:           |  
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 I thought we had this in our tracker already, but perhaps we only
 discussed it.

 spatial_ref_sys is a semi-postgis / semi user-defined.

 We have been battling the issue of how to separate these two so that
 upgrade is a bit less painless for as far back as I can remember.  It
 wasn't so much of an issue when we had fewer users but now is becoming
 more of a major one.

 1) strk proposed a while back making it a view and having two tables:
 spatial_ref_sys_master, spatial_ref_sys_custom  and then spatial_ref_sys
 would be the union of the 2 and people would put all their custom entries
 in spatial_ref_sys_custom


 2) I didn't like that idea too much because it might break apps and
 proposed we just have a bit switch instead where we would tag all the ones
 we input is postgis installed.  And the remaining ones we would default
 user input to true so in theory nothing would change except for people
 being lazy and doing an insert like

 INSERT INTO spatial_ref_sys VALUES (... without qualifying the tables.

 strk also pointed out it might break the postgis_restore which assumes the
 structure.

 3)  I have a third idea which is a bit of a morph of the two.  Keep
 spatial_ref_sys as a table, but add another table for custom spatial
 ref_sys records.  Have custom spatial_ref_sys inherit from spatial_ref_sys
 but put in a DO INSTEAD OF trigger in spatial_ref_sys that we would put in
 after we have inserted all our records.  The do instead would push updates
 to the custom_spatial_ref_sys

 (It's really a revision of strk's #1)

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Ticket URL: <http://trac.osgeo.org/postgis/ticket/1831>
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