How to load data fetched via ajax faster?

Question

Currently data is fetched as an array form PHP script. SO I find that for 40 set of data it take about 20 seconds to load. I guess it's because ajax has to wait till until all the results gathered. If the data set increased to hundreds, I think it's gonna slow sown a lot.

So I did some research on how to decrease the loading time thus come across parallel ajax request. I think it would be helpful, for multiple requests.For single request but hundreds and thousands of data fetched, is there a way to increase the speed?

JS :

$(function() {
    $.ajax({
        dataType: "json",
        url: 'showAllTutor.php',
        success: function(data) {
            console.log(data.length);
            var j=0;
            for (i = 0; i < data.length; i++) {
                j++;
                console.log(data[i].name);
            }
        }
    });
});

PHP :

 $sql="SELECT * FROM userinfo,posts WHERE userinfo.UUID = posts.UUID AND posts.p_id > '$last_msg_id'";
        $stmt =connection::$pdo->prepare($sql);
        $stmt->execute();
        $json=array();

        while($row = $stmt->fetch()) {
             $total = $row['reviewPlus']+ $row['reviewNeg'];
             array_push($json,array("name"=>$row['name'],"subject"=>$row['subname'],"subid"=>$row['subID'],"rate"=>$row['pricing'],"dateposted"=>$row['datePosted'],"location"=>$row['location'],"contact"=>$row['phone'],"morning"=>$row['morning'],"afternoon"=>$row['afternoon'],"evening"=>$row['evening'],"postId"=>$row['p_id'],"total"=>$total,"plus"=>$row['reviewPlus'],"user"=>$row['UUID']));                
        }       
    }       
    echo json_encode($json);

Answer 1

Loading time might be because of multiple loops in your code, while loop in php and for loop in jquery which increase the execution time,

I suggest you to avoid while loop in your php code collect all data using fetchAll statement

$data = $stmt->fetchAll(PDO::FETCH_ASSOC);
echo json_encode($data);

and make your $total calculation in yours jquery for loop,

This might help, Happy coding.