Question

I am using node-mysql module (https://github.com/felixge/node-mysql) OR (http://utahjs.com/2010/09/22/nodejs-and-mysql-introduction/) .

Is this API handling connection pooling as well?

I mean with every user request I am calling Client.connect() to query the MySQL and to release the connection: Client.end().

Is this the right way, or should I connect/disconnect only once in a code.

I am learning from this document: https://github.com/felixge/node-mysql/blob/master/Readme.md

Answer 1

Update: Feb 2013 – pool support has been added to node-mysql, see docs

Example using built-in pool:

var pool = require('mysql').createPool(opts);

pool.getConnection(function(err, conn) {
  conn.query('select 1+1', function(err, res) {
    conn.release();
  });
});

Pre 2013 solutions:

You can use node-pool or mysql-pool or use your own simple round-robin pool

function Pool(num_conns)
{
    this.pool = [];
    for(var i=0; i < num_conns; ++i)
        this.pool.push(createConnection()); // your new Client + auth
    this.last = 0;
}

Pool.prototype.get = function()
{
    var cli = this.pool[this.last];
    this.last++;
    if (this.last == this.pool.length) // cyclic increment
       this.last = 0;
    return cli;
}

now you can hope to have all queries callbacks to execute in 1 second:

var p = new Pool(16);
for (var i=0; i < 10; ++i)
{
    p.get().query('select sleep(1)', function() { console.log('ready'); } ); // server blocks for 1 second
}