Add migration to add id column and primary key to join tables

This migration also creates the sequence using the current region.

Because of this, records in a global (replicated) environment need
to be removed as we will not be able to guarentee that the new
primary key assigned in the regional database is set to the same
row in the global database at the time of the migration.

Also, only delete rows on the global region if they came from a different region

This will preserve rows that belong to the global region
like ones in seeded tables like `miq_groups_users` or if
someone is managing some environment using the global database.

db/migrate/20160406195810_add_id_primary_key_to_join_tables.rb

@@ -0,0 +1,99 @@
+class AddIdPrimaryKeyToJoinTables < ActiveRecord::Migration[5.0]
+  JOIN_TABLES = %w(
+    conditions_miq_policies
+    key_pairs_vms
+    miq_roles_features
+    security_groups_vms
+    storages_vms_and_templates
+    miq_groups_users
+    cloud_tenants_vms
+    customization_scripts_operating_system_flavors
+    configuration_locations_configuration_profiles
+    configuration_organizations_configuration_profiles
+    configuration_profiles_configuration_tags
+    configuration_tags_configured_systems
+    container_groups_container_services
+    direct_configuration_profiles_configuration_tags
+    direct_configuration_tags_configured_systems
+    network_ports_security_groups
+  ).freeze
+
+  COMPOSITE_KEY_MAP = {
+    "cloud_tenants_vms"                                  => "cloud_tenant_id, vm_id",
+    "conditions_miq_policies"                            => "miq_policy_id, condition_id",
+    "configuration_locations_configuration_profiles"     => "configuration_location_id, configuration_profile_id",
+    "configuration_organizations_configuration_profiles" => "configuration_organization_id, configuration_profile_id",
+    "configuration_profiles_configuration_tags"          => "configuration_profile_id, configuration_tag_id",
+    "configuration_tags_configured_systems"              => "configured_system_id, configuration_tag_id",
+    "container_groups_container_services"                => "container_service_id, container_group_id",
+    "customization_scripts_operating_system_flavors"     => "customization_script_id, operating_system_flavor_id",
+    "direct_configuration_profiles_configuration_tags"   => "configuration_profile_id, configuration_tag_id",
+    "direct_configuration_tags_configured_systems"       => "configured_system_id, configuration_tag_id",
+    "key_pairs_vms"                                      => "authentication_id, vm_id",
+    "miq_groups_users"                                   => "miq_group_id, user_id",
+    "miq_roles_features"                                 => "miq_user_role_id, miq_product_feature_id",
+    "network_ports_security_groups"                      => "network_port_id, security_group_id",
+    "security_groups_vms"                                => "security_group_id, vm_id",
+    "storages_vms_and_templates"                         => "storage_id, vm_or_template_id"
+  }.freeze
+
+  class MiqRegion < ApplicationRecord
+    self.inheritance_column = :_type_disabled
+  end
+
+  def up
+    say_with_time("Removing composite primary keys from join tables") do
+      COMPOSITE_KEY_MAP.keys.each do |table|
+        execute("ALTER TABLE #{table} DROP CONSTRAINT #{table}_pkey")
+      end
+    end
+
+    JOIN_TABLES.each do |t|
+      delete_remote_region_rows(t) if on_replication_target?
+
+      say_with_time("Add primary key \"id\" to #{t}") do
+        execute <<-SQL
+          CREATE SEQUENCE #{sequence_name(t)} START #{seq_start_value}
+        SQL
+
+        execute <<-SQL
+          ALTER TABLE #{t} ADD COLUMN id BIGINT PRIMARY KEY
+          DEFAULT NEXTVAL('#{sequence_name(t)}')
+        SQL
+
+        execute <<-SQL
+          ALTER SEQUENCE #{sequence_name(t)} OWNED BY #{t}.id
+        SQL
+      end
+    end
+  end
+
+  def down
+    JOIN_TABLES.each do |t|
+      remove_column t.to_sym, :id
+    end
+
+    COMPOSITE_KEY_MAP.each do |table, key|
+      execute("ALTER TABLE #{table} ADD PRIMARY KEY (#{key})")
+    end
+  end
+
+  def delete_remote_region_rows(table)
+    model = Class.new(ApplicationRecord) { self.table_name = table }
+    col = model.column_names_symbols.first
+    model.where.not(col => model.region_to_range(model.my_region_number)).delete_all
+  end
+
+  def on_replication_target?
+    MiqRegion.select(:region).distinct.count > 1
+  end
+
+  def sequence_name(table)
+    "#{table}_id_seq"
+  end
+
+  def seq_start_value
+    val = ApplicationRecord.rails_sequence_start
+    val == 0 ? 1 : val
+  end
+end

spec/migrations/20160406195810_add_id_primary_key_to_join_tables_spec.rb

@@ -0,0 +1,72 @@
+require_migration
+
+describe AddIdPrimaryKeyToJoinTables do
+  let(:connection)  { described_class.connection }
+  let(:region_stub) { migration_stub(:MiqRegion) }
+
+  migration_context :up do
+    context "on a replication target" do
+      let(:remote_region_id)          { ApplicationRecord.my_region_number + 1 }
+      let(:remote_region_range_start) { ApplicationRecord.region_to_range(remote_region_id).begin }
+      let(:my_region_id)          { ApplicationRecord.my_region_number }
+      let(:my_region_range_start) { ApplicationRecord.region_to_range(my_region_id).begin }
+
+      before do
+        region_stub.create!(:id => my_region_range_start, :region => my_region_id)
+        region_stub.create!(:id => remote_region_range_start, :region => remote_region_id)
+      end
+
+      it "removes rows from remote regions" do
+        described_class::JOIN_TABLES.each do |table|
+          connection.select_value <<-SQL
+            INSERT INTO #{table} VALUES (#{my_region_range_start}, #{my_region_range_start + 1})
+          SQL
+
+          connection.select_value <<-SQL
+            INSERT INTO #{table} VALUES (#{remote_region_range_start}, #{remote_region_range_start + 1})
+          SQL
+        end
+
+        migrate
+
+        described_class::JOIN_TABLES.each do |table|
+          connection.select_all("SELECT * FROM #{table}").each do |row|
+            row.each do |k, v|
+              expect(ApplicationRecord.id_in_current_region?(v)).to be(true), <<-EOS.lstrip
+                #{k} value (#{v}) in table #{table} is not in the correct region
+              EOS
+            end
+          end
+        end
+      end
+    end
+
+    it "assigns an id in the correct range" do
+      described_class::JOIN_TABLES.each_with_index do |table, i|
+        connection.select_value <<-SQL
+          INSERT INTO #{table} VALUES (#{i}, #{i + 1})
+        SQL
+      end
+
+      migrate
+
+      described_class::JOIN_TABLES.each do |table|
+        expect(connection.primary_keys(table)).to eq(["id"])
+
+        connection.select_all("SELECT * FROM #{table}").each do |row|
+          expect(ApplicationRecord.id_in_current_region?(row["id"])).to be true
+        end
+      end
+    end
+  end
+
+  migration_context :down do
+    it "recreates the composite primary key" do
+      migrate
+
+      described_class::JOIN_TABLES.each do |table|
+        expect(connection.primary_keys(table).count).to eq(2)
+      end
+    end
+  end
+end