require_dependency 'migration/base_dropper' module Migration class Migration::TableDropper < BaseDropper def self.delayed_drop(table_name:, after_migration:, delay: nil, on_drop: nil) validate_table_name(table_name) TableDropper.new(table_name, nil, after_migration, delay, on_drop).delayed_drop end def self.delayed_rename(old_name:, new_name:, after_migration:, delay: nil, on_drop: nil) validate_table_name(old_name) validate_table_name(new_name) TableDropper.new(old_name, new_name, after_migration, delay, on_drop).delayed_drop end def self.read_only_table(table_name) create_readonly_function(table_name) ActiveRecord::Base.exec_sql <<~SQL CREATE TRIGGER #{readonly_trigger_name(table_name)} BEFORE INSERT OR UPDATE OR DELETE OR TRUNCATE ON #{table_name} FOR EACH STATEMENT EXECUTE PROCEDURE #{readonly_function_name(table_name)}; SQL end private def initialize(old_name, new_name, after_migration, delay, on_drop) super(after_migration, delay, on_drop) @old_name = old_name @new_name = new_name end def droppable? builder = SqlBuilder.new(<<~SQL) SELECT 1 FROM INFORMATION_SCHEMA.TABLES /*where*/ LIMIT 1 SQL builder.where(new_table_exists) if @new_name.present? builder.where("table_schema = 'public'") .where(previous_migration_done) .exec(old_name: @old_name, new_name: @new_name, delay: "#{@delay} seconds", after_migration: @after_migration).to_a.length > 0 end def new_table_exists <<~SQL EXISTS( SELECT 1 FROM INFORMATION_SCHEMA.TABLES WHERE table_schema = 'public' AND table_name = :new_name ) SQL end def execute_drop! ActiveRecord::Base.exec_sql("DROP TABLE IF EXISTS #{@old_name}") ActiveRecord::Base.exec_sql <<~SQL DROP FUNCTION IF EXISTS #{BaseDropper.readonly_function_name(@old_name)} CASCADE; SQL end end end