MySQL File Download Speed Limit - php

Question

I have all my files stored in a mysql database as blobs. I am trying to add a speed limit to the rate at which a user can download them through our PHP website. I have tried to use the "sleep(1);" method, it does not seem to work or i am not doing it right. So if anyone knows a way to limit the speed, i would love your help.
Here is my download code
$query=mysql_query("SELECT * FROM file_servers WHERE id='$file_server_id'");
$fetch=mysql_fetch_assoc($query);
$file_server_ip=$fetch['ip'];
$file_server_port=$fetch['port'];
$file_server_username=$fetch['username'];
$file_server_password=$fetch['password'];
$file_server_db=$fetch['database_name'];
$connectto=$file_server_ip.":".$file_server_port;
if (!$linkid = #mysql_connect($connectto, $file_server_username, $file_server_password, true))
{
die("Unable to connect to storage server!");
}
if (!mysql_select_db($file_server_db, $linkid))
{
die("Unable to connect to storage database!");
}
$nodelist = array();
// Pull the list of file inodes
$SQL = "SELECT id FROM file_data WHERE file_id='$file_id' order by id";
if (!$RES = mysql_query($SQL, $linkid))
{
die("Failure to retrive list of file inodes");
}
while ($CUR = mysql_fetch_object($RES))
{
$nodelist[] = $CUR->id;
}
// Send down the header to the client
header("Content-Type: $data_type");
header("Content-Length: $size");
header("Content-Disposition: attachment; filename=$name");
// Loop thru and stream the nodes 1 by 1
for ($Z = 0 ; $Z < count($nodelist) ; $Z++)
{
$SQL = "select file_data from file_data where id = " . $nodelist[$Z];
if (!$RESX = mysql_query($SQL, $linkid))
{
die("Failure to retrive file node data");
}
$DataObj = mysql_fetch_object($RESX);
echo $DataObj->file_data;
}

Answer 1

One way of doing this may be the combination of flush and sleep:
read part of what you get from database
output some bytes
flush the output to the user
sleep for 1 second
But also take a loot at throttle function:
http://php.net/manual/en/function.http-throttle.php
It also have an example there. I think it is better suited.

Answer 2

it is in the very last echo line in your code where you would like to implement throtling. Im not familiar with whether php supports throtling output.
if not, you can try to split up that content ($DataObj->file_data) you wish to echo, and echo it little piece by little piece with small pauses in between
and be sure to disable outbut buffering. otherwise all that you echo will not be outputted until the entire script is done.