通过触发器实现跨库同步表数据

文章实现了postgresql和mysql两种数据库的跨库同步数据表。

1.postgresql实现跨库同步表数据

postgresql采用postgres_fdw插件实现跨库同步，在编写跨库同步脚本前，需要先准备好postgres_fdw的执行环境。

1.1安装插件、创建远程服务

如已配置好远程服务，可以忽略此步骤

-- 安装 postgres_fdw 插件 
CREATE EXTENSION postgres_fdw;
 
-- 创建远程服务 
CREATE SERVER remote_server FOREIGN DATA WRAPPER postgres_fdw;
 
-- 查看远程服务
select * from pg_foreign_server ;
 
-- 修改远程服务 
alter server remote_server options (add hostaddr '11.216.10.215', 
                          add port '5432', add dbname 'db_des');

1.2创建需要跨库同步的两个数据表

实现将数据库DATABASE_A中的DEMO_TABLE表数据同步到数据库DATABASE_B中的DEMO_TABLE表

--在数据库DATABASE_A和DATABASE_B中分别创建表--
CREATE TABLE "DEMO_TABLE" (
"id" serial PRIMARY KEY,
"priv_prod_id" int4,
"shr_type_id" int4,
"start_date" date,
"end_date" date,
"commission" numeric(10,4),
"create_by" varchar(10) COLLATE "default",
"create_time" timestamp(6),
"update_by" varchar(10) COLLATE "default",
"update_time" timestamp(6),
"rec_stat" varchar(1) COLLATE "default",
"version" int2
);

1.3创建远程控制表

远程控制表需要与跨库待同步的数据表结构保持一致，能自动将insert、update、delete命令同步在关联跨库表中执行。

------------创建远程控制表-------------------
DROP TABLE IF EXISTS "public"."fdw_DEMO_TABLE";
CREATE FOREIGN TABLE "public"."fdw_DEMO_TABLE" (
  "id" int4,
  "prod_id" int4,
  "shr_type_id" int4,
  "start_date" date,
  "end_date" date,
  "commission" numeric(10,4),
  "create_by" varchar(10) COLLATE "pg_catalog"."default",
  "create_time" timestamp(6),
  "update_by" varchar(10) COLLATE "pg_catalog"."default",
  "update_time" timestamp(6),
  "rec_stat" varchar(1) COLLATE "pg_catalog"."default",
  "version" int2
)
----使用已经配置好的数据库外部服务----------
SERVER "pg_fdw_DEMO_TABLE"
----关联外部数据库服务的数据表，表结构需要与远程控制表一致----------
OPTIONS ("table_name" 'demo_table')
;

1.4创建触发器和函数，实时将数据表中的数据同步到远程控制表

--创建同步函数--
-------delete函数---------
CREATE OR REPLACE FUNCTION "public"."fuc_DEMO_TABLE_delete"()
  RETURNS "pg_catalog"."trigger" AS $BODY$
BEGIN
        DELETE FROM fdw_DEMO_TABLE WHERE id = OLD.id;
        RETURN OLD;
END;
$BODY$
  LANGUAGE plpgsql VOLATILE
  COST 100;
-------insert函数---------     
CREATE OR REPLACE FUNCTION "public"."fuc_DEMO_TABLE_insert"()
  RETURNS "pg_catalog"."trigger" AS $BODY$
BEGIN
        INSERT INTO fdw_DEMO_TABLE ( id, prod_id, shr_type_id, start_date, end_date, commission, create_by, create_time, update_by, update_time, rec_stat, version )
  VALUES(new.id, new.priv_prod_id, new.shr_type_id, new.start_date, new.end_date, new.commission, new.create_by, new.create_time, new.update_by, new.update_time, 
        new.rec_stat, new.version);
        RETURN new;
END;
$BODY$
  LANGUAGE plpgsql VOLATILE
  COST 100;
-------update函数---------  
CREATE OR REPLACE FUNCTION "public"."fuc_DEMO_TABLE_update"()
  RETURNS "pg_catalog"."trigger" AS $BODY$
        BEGIN
         UPDATE fdw_DEMO_TABLE SET prod_id = NEW.priv_prod_id , shr_type_id = NEW.shr_type_id, start_date = NEW.start_date, end_date = NEW.end_date, commission = NEW.commission, create_by = NEW.create_by, create_time = NEW.create_time, update_by = NEW.update_by, update_time = NEW.update_time, rec_stat = NEW.rec_stat, version = NEW.version WHERE id = NEW.id;

        RETURN NEW;
END;
$BODY$
  LANGUAGE plpgsql VOLATILE
  COST 100;
--3.创建触发器--
CREATE TRIGGER "tg_DEMO_TABLE_delete" AFTER DELETE ON "public"."DEMO_TABLE"
FOR EACH ROW
EXECUTE PROCEDURE "fuc_DEMO_TABLE_delete"();

CREATE TRIGGER "tg_DEMO_TABLE_insert" AFTER INSERT ON "public"."DEMO_TABLE"
FOR EACH ROW
EXECUTE PROCEDURE "fuc_DEMO_TABLE_insert"();

CREATE TRIGGER "tg_DEMO_TABLE_update" AFTER UPDATE ON "public"."DEMO_TABLE"
FOR EACH ROW
EXECUTE PROCEDURE "fuc_DEMO_TABLE_update"();

以上就是postgresql跨库同步数据的全部实现

2.MySql实现跨库同步表数据

mysql采用fed的方式实现跨库同步，数据库默认未开启fed功能模块。

2.1开启fed功能

执行 show ENGINES; 语句

Support值为NO，说明未支持该引擎。需修改mysql的配置文件进行设置。

找到mysql的配置文件，在[mysqld]后添加federated即可；添加完成，重启mysql服务再次查询该引擎状态为YES即为支持。

2.2创建需要跨库同步的两个数据表

参照1.2中的执行脚本

2.3创建fed远程控制表