Swapping from Pool to PoolCluster

[adrianblynch]

We're currently using the module like so:

// db.js
var mysql = require("mysql");
var config = require('./config')();
var pool = mysql.createPool(config.database.main);
exports.conn = pool;

Then in our application code:

var db = require('./db');

db.query('SELECT * FROM user', function(err, results) {
    // 
});

We now wish to start using PoolCluster, changing db.js to:

var mysql = require("mysql");
var config = require('./config')();
var poolCluster = mysql.createPoolCluster();

poolCluster.add('db01', config.database.db01);
poolCluster.add('db02', config.database.db02);
poolCluster.add('db03', config.database.db03);

exports.conn = poolCluster;

PoolCluster has no method query(). We'd like to leave the application code the same but we're unsure of how to export the pool cluster.

Any thoughts on how we might do that?

[dougwilson]

It looks like it's a feature that could be added, but if you're in a hurry, you could probably do the following:

poolCluster.query = function query(sql, values, cb) {
  var query = mysql.createQuery(sql, values, cb);

  this.getConnection(function onConnection(err, conn) {
    if (err) {
      query.on('error', function () {});
      query.end(err);
      return;
    }

    // Release connection based off event
    query.once('end', function() {
      conn.release();
    });

    conn.query(query);
  });

  return query;
};

If we added a PoolCluster.prototype.query, that would be very close to what it would be :)

[dougwilson]

Now that I have learned a little more about the PoolCluster, what you what if definitely possible (sorry it took me so long to realize this):

var mysql = require("mysql");
var config = require('./config')();
var poolCluster = mysql.createPoolCluster();

poolCluster.add('db01', config.database.db01);
poolCluster.add('db02', config.database.db02);
poolCluster.add('db03', config.database.db03);

exports.conn = poolCluster.of('*');

[bjshijh]

I don't think it (means exports.conn = poolCluster.of('*'); ) works.