Add unique constraint to zone origin

#475

db/migrate/20170424115801_add_unique_index_to_zone_origin.rb

@@ -0,0 +1,13 @@
+class AddUniqueIndexToZoneOrigin < ActiveRecord::Migration
+  def up
+    execute <<-SQL
+      ALTER TABLE zones ADD CONSTRAINT unique_zone_origin UNIQUE (origin)
+    SQL
+  end
+
+  def down
+    execute <<-SQL
+      ALTER TABLE zones DROP CONSTRAINT unique_zone_origin
+    SQL
+  end
+end

db/schema-read-only.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20170422142116) do
+ActiveRecord::Schema.define(version: 20170424115801) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -1143,4 +1143,6 @@ ActiveRecord::Schema.define(version: 20170422142116) do
     t.text     "a4_records"
   end
 
+  add_index "zones", ["origin"], name: "unique_zone_origin", unique: true, using: :btree
+
 end

db/structure.sql

@@ -3952,6 +3952,14 @@ ALTER TABLE ONLY settings
     ADD CONSTRAINT settings_pkey PRIMARY KEY (id);
 
 
+--
+-- Name: unique_zone_origin; Type: CONSTRAINT; Schema: public; Owner: -; Tablespace: 
+--
+
+ALTER TABLE ONLY zones
+    ADD CONSTRAINT unique_zone_origin UNIQUE (origin);
+
+
 --
 -- Name: users_pkey; Type: CONSTRAINT; Schema: public; Owner: -; Tablespace: 
 --
@@ -5221,3 +5229,5 @@ INSERT INTO schema_migrations (version) VALUES ('20170422130054');
 
 INSERT INTO schema_migrations (version) VALUES ('20170422142116');
 
+INSERT INTO schema_migrations (version) VALUES ('20170424115801');
+