Heroku + Apartment PG::Error: ERROR: function pg_stat_statements_reset() does not exist

Question

I use Apartment gem in Rails 4 to support multi-tenancy in Postgres 9.3.3 on Heroku.

An error is occurred when Apartment gem creates a new tenant.

Deep investiga

Answer 1

When a new schema is created Postgres is trying to reset stats by executing the function pg_stat_statements_reset()

By default, this function can only be executed by superusers (from original doc).

Heroku doesn't give you superuser privileges. So you need to disable extension pg_stat_statements.

Solution 1 - Quick hot fix directly in DB

1. Access the Rails Console for your Heroku app:

   heroku run rails c

2. Execute SQL statement in schema public:

   ActiveRecord::Base.connection.execute("DROP EXTENSION pg_stat_statements;")

Solution 2 - via migration

1. Check the file db/schema.rb. Most probably it contains a line

   enable_extension "pg_stat_statements"

2. Create a migration file

   rails g migration DropExtensionPgStatStatements

3. define self.up method

   def self.up disable_extension "pg_stat_statements" end

4. apply the migration

   rake db:migrate

5. Now the file db/schema.rb should not contain that line

6. Commit changes (schema and migration files) and deploy to Heroku

   rake deploy:production:migrations

Regarding the rake task see deploy.rake