tag implications: convert descendant_names to array (#3987).

db/migrate/20181114180205_change_descendant_names_to_array_on_tag_implications.rb

@@ -0,0 +1,13 @@
+class ChangeDescendantNamesToArrayOnTagImplications < ActiveRecord::Migration[5.2]
+  def up
+    TagImplication.without_timeout do
+      change_column :tag_implications, :descendant_names, "text[]", using: "string_to_array(descendant_names, ' ')::text[]", default: "{}"
+    end
+  end
+
+  def down
+    TagImplication.without_timeout do
+      change_column :tag_implications, :descendant_names, "text", using: "array_to_string(descendant_names, ' ')", default: nil
+    end
+  end
+end

db/structure.sql

@@ -3012,7 +3012,7 @@ CREATE TABLE public.tag_implications (
     id integer NOT NULL,
     antecedent_name character varying NOT NULL,
     consequent_name character varying NOT NULL,
-    descendant_names text NOT NULL,
+    descendant_names text[] DEFAULT '{}'::text[] NOT NULL,
     creator_id integer NOT NULL,
     creator_ip_addr inet NOT NULL,
     forum_topic_id integer,
@@ -7572,6 +7572,7 @@ INSERT INTO "schema_migrations" (version) VALUES
 ('20180916002448'),
 ('20181108162204'),
 ('20181108205842'),
-('20181113174914');
+('20181113174914'),
+('20181114180205');