add a sync/block option for DDL

[wey-gu]

Introduction

If an option like sync=true is supported for DDL, the application layer could be quite straightforward to enable: create scheme --> insert data. Rather than the implementation of wait/retry.

Contents

This is a common mind model change from non-distributed graphdb to nebulagraph, we could add this support to not request users think/learn/implement too much.

Related work