Make sure views are included in the hierarchical order (#72)

* Make sure views are included in the hierarchical order
* Remove ActsAsHypertable as a default module on ActiveRecord::Base.

README.md

@@ -319,6 +319,12 @@ which will correctly handle schema dumping.
 
 ### Enable ActsAsHypertable
 
+Create your `config/initializers/timescaledb.rb` file and add the following line:
+
+```ruby
+ActiveRecord::Base.extend Timescaledb::ActsAsHypertable
+```
+
 You can declare a Rails model as a Hypertable by invoking the `acts_as_hypertable` macro. This macro extends your existing model with timescaledb-related functionality.
 model:
 
@@ -330,6 +336,39 @@ end
 
 By default, ActsAsHypertable assumes a record's _time_column_ is called `created_at`.
 
+You may isolate your hypertables in another database, so, creating an abstract
+layer for your hypertables is a good idea:
+
+```ruby
+class Hypertable < ActiveRecord::Base
+  self.abstract_class = true
+
+  extend Timescaledb::ActsAsHypertable
+
+  establish_connection :timescaledb
+end
+```
+
+And then, you can inherit from this model:
+
+```ruby
+class Event < Hypertable
+  acts_as_hypertable time_column: "time"
+end
+```
+
+Or you can include only when you're going to use them:
+
+```ruby
+class Event < ActiveRecord::Base
+  extend Timescaledb::ActsAsHypertable
+
+  establish_connection :timescaledb
+
+  acts_as_hypertable time_column: "time"
+end
+```
+
 ### Options
 
 If you are using a different time_column name, you can specify it as follows when invoking the `acts_as_hypertable` macro:
@@ -435,6 +474,7 @@ define in `spec/rspec_helper.rb`:
 
 ```ruby
 config.before(:suite) do
+
   hypertable_models = ActiveRecord::Base.descendants.select(&:acts_as_hypertable?)
 
   hypertable_models.each do |klass|

lib/timescaledb/acts_as_hypertable.rb

@@ -62,4 +62,3 @@ def acts_as_hypertable(options = {})
   end
 end
 
-ActiveRecord::Base.extend Timescaledb::ActsAsHypertable

lib/timescaledb/continuous_aggregates.rb

@@ -14,6 +14,30 @@ class ContinuousAggregate < ::Timescaledb::ApplicationRecord
         total: count
       }
     end
+
+    scope :hierarchical, -> do
+      with_recursive = <<~SQL
+        WITH RECURSIVE caggs AS (
+          SELECT mat_hypertable_id, parent_mat_hypertable_id, user_view_name
+            FROM _timescaledb_catalog.continuous_agg
+          UNION ALL
+          SELECT continuous_agg.mat_hypertable_id, continuous_agg.parent_mat_hypertable_id, continuous_agg.user_view_name
+            FROM _timescaledb_catalog.continuous_agg
+        JOIN caggs ON caggs.parent_mat_hypertable_id = continuous_agg.mat_hypertable_id
+        )
+        SELECT * FROM caggs
+        ORDER BY mat_hypertable_id
+      SQL
+      views = unscoped
+        .select("distinct user_view_name")
+        .from("(#{with_recursive}) as caggs")
+        .pluck(:user_view_name)
+        .uniq
+
+      views.map do |view|
+        find_by(view_name: view)
+      end
+    end
   end
   ContinuousAggregates = ContinuousAggregate
 end

lib/timescaledb/schema_dumper.rb

@@ -154,7 +154,7 @@ def timescale_index_options_for(hypertable)
     def timescale_continuous_aggregates(stream)
       return unless Timescaledb::ContinuousAggregates.table_exists?
 
-      Timescaledb::ContinuousAggregates.all.find_each do |aggregate|
+      Timescaledb::ContinuousAggregates.hierarchical.each do |aggregate|
         refresh_policies_opts = if (refresh_policy = aggregate.jobs.refresh_continuous_aggregate.first)
           interval = timescale_interval(refresh_policy.schedule_interval)
           end_offset = timescale_interval(refresh_policy.config["end_offset"])

spec/spec_helper.rb

@@ -8,7 +8,9 @@
 require_relative "support/active_record/models"
 require_relative "support/active_record/schema"
 
-Dotenv.load!
+Dotenv.load! if File.exists?(".env")
+
+# Establish a connection for testing
 
 ActiveRecord::Base.establish_connection(ENV['PG_URI_TEST'])
 Timescaledb.establish_connection(ENV['PG_URI_TEST'])

spec/support/active_record/models.rb

@@ -1,3 +1,5 @@
+ActiveRecord::Base.extend Timescaledb::ActsAsHypertable
+
 class Event < ActiveRecord::Base
   self.primary_key = "identifier"
 

spec/timescaledb/schema_dumper_spec.rb

@@ -6,6 +6,12 @@
                   identifier as label,
                   count(*) as value").group("1,2")
   end
+  let(:query_daily) do
+    Event
+      .from("event_counts")
+      .select("time_bucket('1d', time) as time,
+              sum(value) as value").group("1")
+  end
 
   context "schema" do
     it "should include the timescaledb extension" do
@@ -71,8 +77,10 @@
   end
 
   it "dumps a create_continuous_aggregate for a view in the database" do
+    con.execute("DROP MATERIALIZED VIEW IF EXISTS event_daily_counts")
     con.execute("DROP MATERIALIZED VIEW IF EXISTS event_counts")
     con.create_continuous_aggregate(:event_counts, query, materialized_only: true, finalized: true)
+    con.create_continuous_aggregate(:event_daily_counts, query_daily, materialized_only: true, finalized: true)
 
     if defined?(Scenic)
       Scenic.load # Normally this happens in a railtie, but we aren't loading a full rails env here
@@ -93,6 +101,9 @@
     caggs_creation = dump.index('create_continuous_aggregate("event_counts"')
 
     expect(hypertable_creation).to be < caggs_creation
+
+    caggs_dependent_creation = dump.index('create_continuous_aggregate("event_daily_counts"')
+    expect(caggs_creation).to be < caggs_dependent_creation
   end
 
   describe "dumping hypertable options" do