var i = 0;
exports.handler = function (event, context) {
    context.succeed(++i);
};

> 0
> 1
> 2
> 0
> 1
> 0
> 3
> 2
> 4
> 1
> 2

var MySQL = require('mysql');
var pool = MySQL.createPool({
   connectionLimit: 10,
   host: '*****',
   user: '*****',
   pass: '*****',
   database: '*****'
});

function logError (err, callback) {
    console.error(err);
    callback('Unable to perform operation');
}

exports.handler = function (event, context) {
    connectionPool.getConnection(function (err, connection) {
        err && logError(err, context.fail);
        connection.query('CALL someSP(?)', [event.user_id], function (err, data) {
            err && logError(err, context.fail);
            context.succeed(data[0]);
            connection.release();
        });
    });
};