Fast inserting to array/sql - php

Question

I got this code
$i = -1;
$random_string = array();
while (sizeof($random_string) < 1600000) {
$i++;
$zmienna = generatePassword();
if (!in_array($zmienna, $random_string))
$random_string[$i] = $zmienna;
else
continue;
}
//print_r($random_string);
foreach ($random_string as $value) {
$sql = "INSERT INTO `kody`(`kod`) VALUES ('$value')";
mysql_query($sql, $con);
}
But it will take a lot of hours to insert it to databse, or even to array. Do someone know how to improve this code?

Answer 1

Well, in_array() is rather expensive. Use a hash instead of a simple array, and then you can use isset() instead of in_array().
Also, don't use things like sizeof() and count() as loop conditions. Instead, just use a simple for ($i = 0; $i < 1600000; ++$i) { ... } array.
Depending on your web host permissions, another significant optimization would be to use fputcsv() to write your array to disk and then make use of MySQL's LOAD DATA INFILE to load the contents into your database, instead of generating 1.6 million queries.

Answer 2

Yes, use one query to insert all of them at once with an SQL multi-insert:
$values = "('" . implode( "'), ('", $random_string) . "')";
$sql="INSERT INTO `kody`(`kod`) VALUES " . $values;
mysql_query($sql,$con);
As drrcknlsn very correctly points out, in_array() is inefficient, as it performs a linear O(n) search on the array. Here is how you can fix that (which is a hash implementation):
while( sizeof($random_string) < 1600000) {
$i++;
$zmienna = generatePassword();
if( !isset( $random_string[$zmienna]))
$random_string[$zmienna] = $zmienna;
else
continue;
}
Now, you can use the above code to generate a single SQL query, and this should run much, much faster.

Answer 3

The problem is probably that it's trying to update the INDEX after each insert. Try using transactions. This will only update the INDEX once (after COMMIT) is called. This will also let you ROLLBACK if something goes wrong.
mysql_query("SET AUTOCOMMIT=0");
mysql_query("START TRANSACTION");
foreach($random_string as $value)
{
$sql="INSERT INTO `kody`(`kod`) VALUES ('$value')";
mysql_query($sql,$con);
}
mysql_query("COMMIT");