Make select inside a setInterval and fill an array in nodejs

I'm making an application that needs to be checking in the database if there was any change using nodejs. The application works, however, when I have more than one record in the table, it gets duplicate data that I keep in an array. For example: I have 2 records in the table, in the first loop of setInterval, in console.log () it shows me Array [2], in the second loop, Array [4] and so on. Does anyone know a way to build an array of data inside the setInterval that does not duplicate? My code looks like this:

var app = express();
var server = http.createServer(app);
var io = SocketIO.listen(server);

var Agenda = {};
var horarios = [];

setInterval(function(){

var query = connection.query('SELECT * FROM agenda WHERE id = 32');
query
.on('error', function(err) {
    console.log(err);
})
.on('result', function(ag) {
    Agenda = ag;
})
.on('end', function() {
})

var query2 = connection.query('SELECT * FROM horarios WHERE id_agenda = 32 ');
query2
.on('error', function(err) {
    console.log(err);
})
.on('result', function(hr) {        
    horarios.push(hr);
})
.on('end', function() { 
})    
Agenda.horario = horarios;
//console.log(JSON.stringify(Agenda));
if(horarios.length > 0){
    io.sockets.emit('time', {time: JSON.stringify(Agenda)});
}    

},3000);