我在
Postgresql 9.1数据库上有一个“文章”表和一个通知每个插入的通道的触发器.
我想创建一个node.js脚本来捕获这些插入并使用Socket.io将通知推送到连接的客户端.到目前为止,我正在使用node-postgres模块LISTEN到通道,但似乎LISTEN查询在大约10-15秒后超时并停止捕获插入.我可以在超时发生时查询新的监听,但我不确定如何正确实现延续.
CREATE FUNCTION article_insert_notify() RETURNS trigger AS $$ BEGIN NOTIFY "article_watcher"; RETURN NULL; END; $$LANGUAGE plpgsql;
触发：
CREATE TRIGGER article_insert_trigger AFTER INSERT ON article FOR EACH ROW EXECUTE PROCEDURE article_insert_notify();
而node.js代码：
var pg = require ('pg'),pgConnection = "postgres://user:pass@localhost/db"
pg.connect(pgConnection,function(err,client) {
client.query('LISTEN "article_watcher"');
client.on('notification',function(data) {
console.log(data.payload);
});
});
如何确保全职LISTEN或如何捕获这些超时以重新发出侦听查询？或者,node-postgres以外的模块可能提供更合适的工具吗？
我在node-postgres repo上得到了我的问题的答案.引用Brianc：
原文链接：https://www.f2er.com/postgresql/191631.htmlpg.connect is use to create pooled connections. Using a connection
pool connection for listen events really isn’t supported or a good
idea though.
[…]
To ‘listen’ a connection by definition must stay open permanently. For
a connection to stay open permanently it can never be returned to the
connection pool.
在这种情况下,正确的监听方式是使用独立客户端：
var pg = require ('pg'),pgConnectionString = "postgres://user:pass@localhost/db";
var client = new pg.Client(pgConnectionString);
client.connect();
client.query('LISTEN "article_watcher"');
client.on('notification',function(data) {
console.log(data.payload);
});
