ppg_fdw:分布式并行查询引擎，基于 PG 的 fdw 和 hooks

ppg_fdw A distributed parallel query engine, based on fdw and hooks of PG. Our idea is to create a shared-nothing system, which is composed many pgsql servers. For these pgsql servers, one server (we call it DQ, it is short for Distributed parallel Query engine)need to install ppg_fdw (please follow the steps following), and the others store table which is sharded horizontally. (Currently, we sh