Fix migrations with the same timestamps in multiple databases

In rails#42604 we added functionality that would sort the migrations by
timestamp so that if there were 2 migrations in 2 databases that were
dependent on one another they would be run in timestamp order rather
than in cluster order.

While debugging another issue I realized that if the timestamps are the
same that only one of the migrations will get run. This fixes the issue
by collecting all the db configs for a version so that we get the entire
list.

Co-authored-by: John Crepezzi <[email protected]>

Author: eileencodes

activerecord/lib/active_record/railties/databases.rake

@@ -94,9 +94,11 @@ db_namespace = namespace :db do
       original_db_config = ActiveRecord::Base.connection_db_config
       mapped_versions = ActiveRecord::Tasks::DatabaseTasks.db_configs_with_versions(db_configs)
 
-      mapped_versions.sort.each do |version, db_config|
-        ActiveRecord::Base.establish_connection(db_config)
-        ActiveRecord::Tasks::DatabaseTasks.migrate(version)
+      mapped_versions.sort.each do |version, db_configs|
+        db_configs.each do |db_config|
+          ActiveRecord::Base.establish_connection(db_config)
+          ActiveRecord::Tasks::DatabaseTasks.migrate(version)
+        end
       end
     end
 

activerecord/lib/active_record/tasks/database_tasks.rb

@@ -286,7 +286,7 @@ def migrate(version = nil)
       end
 
       def db_configs_with_versions(db_configs) # :nodoc:
-        db_configs_with_versions = {}
+        db_configs_with_versions = Hash.new { |h, k| h[k] = [] }
 
         db_configs.each do |db_config|
           ActiveRecord::Base.establish_connection(db_config)
@@ -295,7 +295,7 @@ def db_configs_with_versions(db_configs) # :nodoc:
 
           versions_to_run.each do |version|
             next if target_version && target_version != version
-            db_configs_with_versions[version] = db_config
+            db_configs_with_versions[version] << db_config
           end
         end
 

railties/test/application/rake/multi_dbs_test.rb

@@ -451,6 +451,42 @@ class ThreeMigration < ActiveRecord::Migration::Current
         end
       end
 
+      test "migrations in different directories can have the same timestamp" do
+        require "#{app_path}/config/environment"
+        app_file "db/migrate/01_one_migration.rb", <<-MIGRATION
+          class OneMigration < ActiveRecord::Migration::Current
+            def change
+	      create_table :posts do |t|
+		t.string :title
+
+		t.timestamps
+	      end
+            end
+          end
+        MIGRATION
+
+        app_file "db/animals_migrate/01_one_migration.rb", <<-MIGRATION
+          class OneMigration < ActiveRecord::Migration::Current
+            def change
+	      create_table :dogs do |t|
+		t.string :name
+
+		t.timestamps
+	      end
+            end
+          end
+        MIGRATION
+
+        Dir.chdir(app_path) do
+          output = rails "db:migrate"
+          entries = output.scan(/^== (\d+).+migrated/).map(&:first).map(&:to_i)
+
+          assert_match(/dogs/, output)
+          assert_match(/posts/, output)
+          assert_equal [1, 1], entries
+        end
+      end
+
       test "db:migrate and db:schema:dump and db:schema:load works on all databases" do
         db_migrate_and_schema_dump_and_load
       end