Get MySql result-set size from query using PHP

Question

Is it possible to get the size of the result-set when doing a query?

I need to set a proper MySql cache_limit (MB) and therefore I am trying out some queries, but I need to know the sizes of the result-sets to fine-tune my cache configurations.

What exactly does query_cache_limit do when measuring the size of a query (or result)...

Any help appreciated!

Thanks

Answer 1

As a rouph estimate you coud try

<?php
// This is only an example, the numbers below will
// differ depending on your system

echo memory_get_usage() . "\n"; // 36640

$a = mysql_fetch_assoc($result);

echo memory_get_usage() . "\n"; // 57960

unset($a);

echo memory_get_usage() . "\n"; // 36744

?>

or

echo strlen(serialize(mysql_fetch_assoc($result)));

Answer 2

I believe Petah's method of using memory_get_usage before and after is probably the easiest way. To get a more accurate result, you could use mb_strlen but you'd need to loop through each row in the result and each field of each row, summing up the total as you go. You'd also need to use the correct encoding.

http://us3.php.net/manual/en/function.mb-strlen.php