plproxy

pig build pkg plproxy         # 构建 RPM 包

pig repo add pgsql -u          # 添加仓库并更新缓存

CREATE EXTENSION plproxy;

CREATE EXTENSION plproxy;

CREATE FUNCTION get_user(i_id int) RETURNS SETOF users AS $$
    CLUSTER 'mycluster';
    RUN ON i_id;
$$ LANGUAGE plproxy;

CREATE FUNCTION get_config(key text) RETURNS text AS $$
    CONNECT 'host=remotehost dbname=config';
    SELECT val FROM config WHERE key = $1;
$$ LANGUAGE plproxy;

CREATE FUNCTION get_user_settings(i_username text) RETURNS SETOF user_settings AS $$
    RUN ON namehash(i_username);
$$ LANGUAGE plproxy;

CREATE FUNCTION get_all_counts() RETURNS SETOF record AS $$
    RUN ON ALL;
    SELECT count(*) FROM users;
$$ LANGUAGE plproxy;

CREATE FUNCTION get_random_quote() RETURNS text AS $$
    RUN ON ANY;
    SELECT quote FROM quotes ORDER BY random() LIMIT 1;
$$ LANGUAGE plproxy;

CREATE SERVER mycluster FOREIGN DATA WRAPPER plproxy
    OPTIONS (
        connection_lifetime '1800',
        p0 'host=node0 dbname=mydb',
        p1 'host=node1 dbname=mydb',
        p2 'host=node2 dbname=mydb',
        p3 'host=node3 dbname=mydb'
    );

CREATE USER MAPPING FOR CURRENT_USER
    SERVER mycluster
    OPTIONS (user 'proxy_user', password 'secret');