1、实例分别i配置dmmal.ini,并且启动MAL_INI=1, 重启数据库服务生效
[MAL_INST1]
MAL_INST_NAME = GRP1_RT_01
MAL_HOST =192.168.100.111
MAL_PORT = 5256
MAL_INST_HOST =192.168.100.111
MAL_INST_PORT = 5236
MAL_DW_PORT = 5266
MAL_INST_DW_PORT = 5246
[MAL_INST2]
MAL_INST_NAME = GRP1_RT_02
MAL_HOST = 192.168.100.112
MAL_PORT = 5256
MAL_INST_HOST = 192.168.100.112
MAL_INST_PORT = 5237
MAL_DW_PORT = 5266
MAL_INST_DW_PORT = 5246

2、创建数据库连接
实例GRP1_RT_01创建连接
create link "SYSDBA"."DM2" connect 'DAMENG' with "SYSDBA" identified by "Dameng@123" using '192.168.100.112/5237';
实例GRP1_RT_02创建连接
create link "SYSDBA"."DM1" connect 'DAMENG' with "SYSDBA" identified by "Dameng@123" using '192.168.100.111/5236';
创建异构数据库连接到oracle
CREATE LINK LINK1 CONNECT 'ORACLE' WITH USER01 IDENTIFIED BY USER01PASSWD USING '127.0.0.1/orcl';

创建用户之间的公共链接(NC用户必须已经创建)
实例GRP1_RT_01创建连接
create public link peerdb connect 'DAMENG' with nc identified by "Dameng@123" using '192.168.100.112/5237';
实例GRP1_RT_02创建连接
create public link peerdb connect 'DAMENG' with nc identified by "Dameng@123" using '192.168.100.111/5236';

验证
select * from dba_db_links;
select * from SYSDBA.TABLE_1@DM1;
INSERT INTO SYSDBA.TABLE_1@DM1 VALUES(4,4,'D',NULL);
UPDATE SYSDBA.TABLE_1@DM1 SET COLUMN_3 = 'd' WHERE COLUMN_1=4;
DELETE FROM SYSDBA.TABLE_1@DM1 WHERE COLUMN_1=4;
select * from NC.TEST@DM2;
select * from NC.TEST@peerdb;
删除数据库连接
DROP LINK DM2;
DROP public LINK peerdb;