avoid recursive query for postgres array types

in large databases, pg_types could be huge, and typelem is not
indexed. so instead just assumed they're named like "_#{base_type_name}"
and add the few that don't follow that, to get a singe direct query

Change-Id: I2c70ba5758c2888d113f0d1de159d9ea01f1d84a
Reviewed-on: https://gerrit.instructure.com/68554
Reviewed-by: James Williams  <jamesw@instructure.com>
Tested-by: Jenkins
Product-Review: Rob Orton <rob@instructure.com>
QA-Review: Rob Orton <rob@instructure.com>

config/initializers/postgresql_adapter.rb

@@ -230,14 +230,12 @@ module PostgreSQLAdapterExtensions
   def initialize_type_map(*args)
     return super if Rails.version >= '4.2'
 
-    known_type_names = OID::NAMES.keys.map { |n| "'#{n}'" }
-    sql = <<-SQL % [known_type_names.join(", "), known_type_names.join(", ")]
-    SELECT t.oid, t.typname, t.typelem, t.typdelim, t.typinput
-     FROM pg_type t
-     LEFT OUTER JOIN pg_type et ON t.typelem=et.oid
-     WHERE
-       t.typname IN (%s)
-       OR et.typname IN (%s)
+    known_type_names = OID::NAMES.keys.map { |n| "'#{n}'" } + OID::NAMES.keys.map { |n| "'_#{n}'" }
+    known_type_names.concat(%w{'name' 'oidvector' 'int2vector' 'line' 'point' 'box' 'lseg'})
+    sql = <<-SQL % [known_type_names.join(", ")]
+    SELECT oid, typname, typelem, typdelim, typinput
+     FROM pg_type
+     WHERE typname IN (%s)
     SQL
     result = execute(sql, 'SCHEMA')
     leaves, nodes = result.partition { |row| row['typelem'] == '0' }