A solution that uses MySQL rand () in PHP to take a random record of CPU 100%

MySQL database has 10 tens of thousands of data, using rand () to extract random 10 records, resulting in high server CPU consumption until the crash ~ Baidu looked at some information, combined with some of their experience, the following solutions:
$idlist = ';
For ($i =1 $i <=20; $i + +) {
if ($i ==1) {
$idlist =mt_rand (3,25216);
}
else{
$idlist = $idlist. Mt_rand (3,25216);
}
}
$query = "SELECT * from table where ID in ($idlist) LIMIT 0,10";

The principle is very simple, is to produce a set of random IDs, and then retrieve this group of IDs corresponding records, after such optimization, the page opening speed significantly faster, the CPU occupancy rate is also small to almost 0, oh ~ the way to use this idea of SQL Server site also optimized a bit!
Speed comparison:
Using rand () to take 10 random records is more than 400 milliseconds, and using the above method as long as 0.6 milliseconds, the difference is too big!!!