[postgis-tickets] [PostGIS] #2382: Can't install postgis ERROR: attempt to redefine parameter "postgis.backend" (was: Can't install postgis extension ERROR: attempt to redefine parameter "postgis.backend")

[PostGIS]

#2382: Can't install postgis ERROR: attempt to redefine parameter
"postgis.backend"
-----------------------------------+----------------------------------------
 Reporter:  robe                   |       Owner:  robe         
     Type:  defect                 |      Status:  new          
 Priority:  medium                 |   Milestone:  PostGIS 2.2.0
Component:  build/upgrade/install  |     Version:  trunk        
 Keywords:                         |  
-----------------------------------+----------------------------------------

Comment(by robe):

 strk,

 When I first saw this problem I thought it was just an extension issue.  I
 just tried the old fashioned way -- installing 2.1.2dev then upgrading
 with postgis_upgrade.sql to 2.2.0 and got the same error


 {{{
 query result with 1 row discarded.



 ERROR:  attempt to redefine parameter "postgis.backend"
 ********** Error **********

 ERROR: attempt to redefine parameter "postgis.backend"
 SQL state: XX000

 }}}

 This is the sfcgal GUC isn't it that switches between geos and sfcgal
 backend.  I'm not sure why it's only an issue upgrading from 2.1 to 2.2
 and not 2.1.1 to 2.1.2dev etc.

 Where is this thing defined.  Doesn't seem to be explicit in the scripts
 so assume it's done in some postgis C function check.

-- 
Ticket URL: <http://trac.osgeo.org/postgis/ticket/2382#comment:11>
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