Checking multiple fields from mysql with jquery AJAX in one call - php

Question

I've got a page that seems to be in full working order, but I'm having major performance issues (think 30 second delay occasionally from these calls) from what I assume is throwing too many individual POST requests to the server.
Am I right in thinking that there's some way of doing it all in one call and that doing so would improve performance, and what's the easiest way of doing it? Perhaps my use of eval() is part of the problem - or maybe my webhost is just shit.
function startCheckAchs(){
//hide the loading alert
$(document).ajaxStop(function(){
$(this).unbind("ajaxStop");
popup('loadingAlert');
});
//load lifeTimeBaked
lifeTimeBaked = loadAch("lifetimebaked");
loadAch("ach_started", "#achStarted", "achstarted");
loadAch("ach_round1", "#achRound1", "achround1");
loadAch("ach_round2", "#achRound2", "achround2");
loadAch("ach_round3", "#achRound3", "achround3");
if( rewards == 1) {
loadAch("ach_baked100", "#achBaked100", "achbaked100");
loadAch("ach_baked500", "#achBaked500", "achbaked500");
loadAch("ach_baked1000", "#achBaked1000", "achbaked1000");
loadAch("ach_nobread", "#achNoBread", "achnobread");
loadAch("ach_nodough", "#achNoDough", "achnodough");
loadAch("ach_noflour", "#achNoFlour", "achnoflour");
loadAch("ach_allach", "#achAllAch", "achallach");
}
}
function loadAch(ach, achDiv, achVar){
$.ajax({
type: "POST",
url: "scripts/loadach.php",
data: {"achievement" : ach},
dataType: "text",
success: function(result){
if ( achDiv && achVar && result == 1){
$(achDiv).show();
eval(achVar + " = 1");
return result;
} else {
return result;
}
}
});
}
Loadach.php:
$achievement=trim($_POST['achievement']);
$user = $_SESSION['userid'];
$query = "SELECT $achievement FROM breadusers WHERE userid='$user'";
$link =#mysql_query($query);
if(!$link){
die('Could not query:' . mysql_error());
}
echo mysql_result($link, 0);
?>

Answer 1

You are currently loading achievements individually, while you should be doing something like:
<?php
$query = "SELECT ach_started, ach_round1 FROM breadusers WHERE userid='$user'";
$link = mysql_query($query);
$results = mysql_fetch_assoc($link);
echo json_encode($results);
?>
Then, in your javascript code, parse the JSON response (setting dataType: "json" should work), loop over the returned object (has keys such as ach_started, ach_round1, etc etc), and show/hide divs as needed.

Answer 2

Unfortunately you are going to have to redesign that.
SQL queries are slow.
Lots of requests make things slow.
See if you can group all of the data for a user in your database. That way you can make one select for all of the data you need.

Answer 3

You could use a multi-dimensional array and fill it with the data needed, send the array with ajax to the php code, and then you could loop through the array in the php code and echo back the desired results.
This way you would only be making 1 ajax call each time but still get the same results. might be faster this way but i have not tested this. =)

Answer 4

Most browsers have a limit on the number of concurrent server requests they can handle.
If you're using sessions, you'll also find that the server can only process a single request for each session at a time, because the session file is locked by each request, and subsequent requests must wait for it to be unlocked either when the first request finishes, or when a session_write_close() is issued by the executing request.