Add config to disable schema dump after migration

* Add a config on Active Record named `dump_schema_after_migration`
* Schema dump doesn't happen if the config is set to false
* Set default value of the config to true
* Set config in generated production environment file to false
* Update configuration guide
* Update CHANGELOG

2 files changed, 10 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/core.rb b/activerecord/lib/active_record/core.rb
index d691192cfd..d9aaf8597f 100644
--- a/activerecord/lib/active_record/core.rb
+++ b/activerecord/lib/active_record/core.rb
@@ -76,6 +76,15 @@ module ActiveRecord
       mattr_accessor :timestamped_migrations, instance_writer: false
       self.timestamped_migrations = true
 
+      ##
+      # :singleton-method:
+      # Specify whether schema dump should happen at the end of the
+      # db:migrate rake task. This is true by default, which is useful for the
+      # development environment. This should ideally be false in the production
+      # environment where dumping schema is rarely needed.
+      mattr_accessor :dump_schema_after_migration, instance_writer: false
+      self.dump_schema_after_migration = true
+
       # :nodoc:
       mattr_accessor :maintain_test_schema, instance_accessor: false
 
diff --git a/activerecord/lib/active_record/railties/databases.rake b/activerecord/lib/active_record/railties/databases.rake
index 561387a179..9be734e88e 100644
--- a/activerecord/lib/active_record/railties/databases.rake
+++ b/activerecord/lib/active_record/railties/databases.rake
@@ -34,7 +34,7 @@ db_namespace = namespace :db do
     ActiveRecord::Migrator.migrate(ActiveRecord::Migrator.migrations_paths, ENV["VERSION"] ? ENV["VERSION"].to_i : nil) do |migration|
       ENV["SCOPE"].blank? || (ENV["SCOPE"] == migration.scope)
     end
-    db_namespace['_dump'].invoke
+    db_namespace['_dump'].invoke if ActiveRecord::Base.dump_schema_after_migration
   end
 
   task :_dump do