code: func NewDDL(ctx context.Context, etcdCli *clientv3.Client, store kv.Storage,
  	infoHandle *infoschema.Handle, hook Callback, lease time.Duration, ctxPool *pools.ResourcePool) DDL {
  	return newDDL(ctx, etcdCli, store, infoHandle, hook, lease, ctxPool)
  }
docs: // NewDDL creates a new DDL.