PHP quickly gets random small arrays in large arrays

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First query the database to get the first 1000 pieces of data, and then randomly remove 4 pieces.

After I finished writing the program, I found that it ran very slowly. Every time I refreshed it, I had to wait a long time for it to come out.

The code is as follows:

$arr = range(1, 100000);
$start = time();
for($i = 0; $i < 100; $i ++){
 $key = mt_rand(0, 99999 - $i);
 $result[] = $arr[$key];
 unset($arr[$key]);
 sort($arr);
}
$end = time( );
echo $end - $start;

The above writing method must be sorted after using unset.

unset will only delete the key value, but the key will be retained.

The improved writing is as follows:

$arr = range(1, 100000);
$start = time();
for($i = 0; $i < 100; $i ++) {
 $key = mt_rand(0, 99999 - $i);
 $result[] = array_splice($arr, $key, 1);
}
$end = time();
echo $end - $start;

Efficiency increased by 3-4 times.

In the group, php