Postgres 在 9.1 之后推出 LISTEN / NOTIFY
创建一个数据表 foo
CREATE TABLE foo (id serial primary key, name varchar);
创建一个 存贮过程
CREATE FUNCTION notify_trigger() RETURNS trigger AS $$
DECLARE
BEGIN
PERFORM pg_notify('watchers', TG_TABLE_NAME || ',id,' || NEW.id );
RETURN new;
END;
$$ LANGUAGE plpgsql;
创建触发器 当存在插入时候
CREATE TRIGGER watched_table_trigger AFTER INSERT ON foo FOR EACH ROW EXECUTE PROCEDURE notify_trigger();
使用 node js 监听
const { Client } = require('pg');
const constr = {
user: 'chris', password: 'postgres', host: '127.0.0.1', port: 5432, database: 'postgres'
};
const client = new Client(constr)
client.connect().then(() => {
console.log('Connected to PostGreSQL database');
client.query('LISTEN watchers');
}).catch((err) => {
console.error('Error connecting to PostGreSQL database', err);
});
client.on('notification', (notification) => {
console.log('Received notification:', notification.payload);
});
process.on('SIGINT', () => {
client.end();
process.exit(0);
});
触发通知
INSERT INTO "public"."foo" ("name") VALUES ('2') RETURNING *
查看看效果
