2 files changed, 15 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
index b2ad4e600d..310d25767b 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
@@ -177,6 +177,12 @@ module ActiveRecord
         false
       end
 
+      # A list of extensions, to be filled in by databases that
+      # support them (at the moment, postgresql)
+      def extensions
+        []
+      end
+
       # QUOTING ==================================================
 
       # Returns a bind substitution value given a +column+ and list of current
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
index 5ce2f1b04c..84e48970ca 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
@@ -605,6 +605,15 @@ module ActiveRecord
         end
       end
 
+      def extensions
+        if supports_extensions?
+          res = exec_query "SELECT extname from pg_extension", "SCHEMA"
+          res.rows.map { |r| res.column_types['extname'].type_cast r.first }
+        else
+          []
+        end
+      end
+
       # Returns the configured supported identifier length supported by PostgreSQL
       def table_alias_length
         @table_alias_length ||= query('SHOW max_identifier_length', 'SCHEMA')[0][0].to_i