PostgreSQL中实现跨库连接的两种方案

CREATE EXTENSION IF NOT EXISTS dblink;

-- 简单查询示例（需提供目标数据库连接信息）
SELECT *
FROM dblink(
  'dbname=target_db user=username password=password host=localhost port=5432',
  'SELECT column1, column2 FROM target_table'
) AS remote_table(column1 datatype, column2 datatype);

-- 带参数的查询示例
SELECT *
FROM dblink(
  'dbname=target_db user=username password=password',
  format('SELECT * FROM target_table WHERE id = %L', 1)
) AS t(column1 datatype, column2 datatype);

CREATE EXTENSION IF NOT EXISTS postgres_fdw;

CREATE SERVER target_server
FOREIGN DATA WRAPPER postgres_fdw
OPTIONS (host 'localhost', port '5432', dbname 'target_db');

CREATE USER MAPPING FOR current_user
SERVER target_server
OPTIONS (user 'username', password 'password');

-- 手动创建外部表
CREATE FOREIGN TABLE remote_table (
  column1 datatype,
  column2 datatype
)
SERVER target_server
OPTIONS (schema_name 'public', table_name 'target_table');

-- 或批量导入远程模式中的所有表
IMPORT FOREIGN SCHEMA public
FROM SERVER target_server
INTO current_schema;

SELECT * FROM remote_table;