PostgreSQL的外部数据封装器fdw用法

postgres=# select version();
             version
------------------------------------------------------------
 PostgreSQL 11.1, compiled by Visual C++ build 1914, 64-bit
(1 行记录)

CREATE EXTENSION postgres_fdw;

grant usage on foreign data wrapper postgres_fdw to u1;

CREATE SERVER foreign_server
    FOREIGN DATA WRAPPER postgres_fdw
    OPTIONS (host '127.0.0.1', port '5432', dbname 'testdb');

CREATE USER MAPPING FOR public
    SERVER foreign_server
    OPTIONS (user 'dbuser', password '123456');

CREATE FOREIGN TABLE foreign_table_t2(id int,name varchar(10))
SERVER foreign_server options(schema_name 'public',table_name 't2');

-- 创建postgresql_fdw扩展
-- Foreign Data Wrapper: postgres_fdw
CREATE FOREIGN DATA WRAPPER postgres_fdw
  
-- 删除该扩展
-- DROP FOREIGN DATA WRAPPER postgres_fdw

-- 创建ods_server服务对接远程数据库的ods_db库
-- Foreign Server: ods_server
CREATE SERVER ods_server
  FOREIGN DATA WRAPPER postgres_fdw
  OPTIONS (host '68.26.1.1', dbname 'ods_db', port '5432');
  
-- 删除该服务  
-- DROP SERVER ods_server;

-- 指定连接远程
-- User Mapping : xdh
CREATE USER MAPPING FOR ods_db SERVER ods_server
  OPTIONS ("user" 'xha', password '123456');
  
-- 删除该指定用户
-- DROP USER MAPPING FOR creditrisk SERVER cscs

CREATE FOREIGN TABLE zha.student(
  id integer,
  name varchar(50),
  age integer,
  sex varchar(20)
)
SERVER ods_server 
OPTIONS(schema_name'ods',table_name 'student_ods');
-- 将该外表的权限按需要赋权给其它用户
GRANT ALL ON TABLE zha.student TO zha;
GRANT SELECT ON TABLE zha.student TO zhb;

-- Materialized View: gzk.student
-- DROP MATERIALIZED VIEW gzk.student;
CREATE MATERIALIZED VIEW gzk.student
AS
  SELECT
    id,
    name,
    age,
    sex
  from zha.student;

-- 全量刷新(先清空表再重新映射数据,刷新时阻塞select! 较快!)
refresh materialized view gzk.student;
-- 增量刷新(全表数据对比更新,刷新时不会阻塞select! 较慢!)
-- 只有当物化视图中存在unique index(唯一索引)的时候，
-- refresh物化视图才能使用增量更新，加入concurrently参数。否则报错。
refresh materiallized view concurrently gzk.student;
-- 报错
-- ERROR: cannot refresh materialized view "gzk.student" concurrently
-- HINT: Create a unique index with no WHERE clause on one 
-- or more columns of the materialized view.
-- 在物化视图上创建unique index(唯一索引,可以以自增主键id为唯一索引)
create unique index uidx_mv_id on gzk.student(id);
refresh materiallized view concurrently gzk.student;
-- 执行成功
-- 实际业务中可选增量刷新，定时执行refresh的方式