correct index on name value to drop long values

db/migrate/20150724165259_add_index_to_post_custom_fields.rb

@@ -1,5 +1,14 @@
 class AddIndexToPostCustomFields < ActiveRecord::Migration
-  def change
-    add_index :post_custom_fields, [:name, :value]
+  def up
+    execute <<SQL
+      CREATE INDEX index_post_custom_fields_on_name_and_value ON post_custom_fields USING btree (name, left(value, 200))
+SQL
+  end
+
+  def down
+    execute <<SQL
+      DROP INDEX index_post_custom_fields_on_name_and_value
+SQL
+
   end
 end

db/migrate/20150728004647_correct_custom_fields_migration.rb

@@ -0,0 +1,15 @@
+class CorrectCustomFieldsMigration < ActiveRecord::Migration
+  def up
+    execute <<SQL
+      DROP INDEX index_post_custom_fields_on_name_and_value
+SQL
+
+    execute <<SQL
+      CREATE INDEX index_post_custom_fields_on_name_and_value ON post_custom_fields USING btree (name, left(value, 200))
+SQL
+  end
+
+  def down
+    # nothing, no point rolling this back, we rewrote history
+  end
+end