DROP INDEX IF EXISTS idx_acl_calendar;
DROP INDEX IF EXISTS idx_acl_group_calendar;
DROP INDEX IF EXISTS idx_acl_user_calendar;
ALTER TABLE acl_entries DROP CONSTRAINT IF EXISTS acl_one_resource;
ALTER TABLE acl_entries DROP COLUMN IF EXISTS resource_calendar_id;
ALTER TABLE acl_entries ADD CONSTRAINT acl_one_resource
    CHECK (num_nonnulls(resource_folder_id, resource_file_id) = 1);