debugging a mysql insert fail in php - php

Question

I'm having problems debugging a failing mysql 5.1 insert under PHP 5.3.4. I can't seem to see anything in the mysql error log or php error logs.
Based on a Yahoo presentation on efficient pagination, I was adding order numbers to posters on my site (order rank, not order sales).
I wrote a quick test app and asked it to create the order numbers on one category. There are 32,233 rows in that category and each and very time I run it I get 23,304 rows updated. Each and every time. I've increased memory usage, I've put ini setting in the script, I've run it from the PHP CLI and PHP-FPM. Each time it doesn't get past 23,304 rows updated.
Here's my script, which I've added massive timeouts to.
include 'common.inc'; //database connection stuff
ini_set("memory_limit","300M");
ini_set("max_execution_time","3600");
ini_set('mysql.connect_timeout','3600');
ini_set('mysql.trace_mode','On');
ini_set('max_input_time','3600');
$sql1="SELECT apcatnum FROM poster_categories_inno LIMIT 1";
$result1 = mysql_query($sql1);
while ($cats = mysql_fetch_array ($result1)) {
$sql2="SELECT poster_data_inno.apnumber,poster_data_inno.aptitle FROM poster_prodcat_inno, poster_data_inno WHERE poster_prodcat_inno.apcatnum ='$cats[apcatnum]' AND poster_data_inno.apnumber = poster_prodcat_inno.apnumber ORDER BY aptitle ASC";
$result2 = mysql_query($sql2);
$ordernum=1;
while ($order = mysql_fetch_array ($result2)) {
$sql3="UPDATE poster_prodcat_inno SET catorder='$ordernum' WHERE apnumber='$order[apnumber]' AND apcatnum='$cats[apcatnum]'";
$result3 = mysql_query($sql3);
$ordernum++;
} // end of 2nd while
}
I'm at a head-scratching loss. Just did a test on a smaller category and only 13,199 out of 17,662 rows were updated. For the two experiments only 72-74% of the rows are getting updated.

Answer 1

I'd say your problem lies with your 2nd query. Have you done an EXPLAIN on it? Because of the ORDER BY clause a filesort will be required. If you don't have appropriate indices that can slow things down further. Try this syntax and sub in a valid integer for your apcatnum variable during testing.
SELECT d.apnumber, d.aptitle
FROM poster_prodcat_inno p JOIN poster_data_inno d
ON poster_data_inno.apnumber = poster_prodcat_inno.apnumber
WHERE p.apcatnum ='{$cats['apcatnum']}'
ORDER BY aptitle ASC;
Secondly, since catorder is just an integer version of the combination of apcatnum and aptitle, it's a denormalization for convenience sake. This isn't necessarily bad, but it does mean that you have to update it every time you add a new title or category. Perhaps it might be better to partition your poster_prodcat_inno table by apcatnum and just do the JOIN with poster_data_inno when you need the actually need the catorder.

Answer 2

Please escape your query input, even if it does come from your own database (quotes and other characters will get you every time). Your SQL statement is incorrect because you're not using the variables correctly, please use hints, such as:
while ($order = mysql_fetch_array($result2)) {
$order = array_filter($order, 'mysql_real_escape_string');
$sql3 = "UPDATE poster_prodcat_inno SET catorder='$ordernum' WHERE apnumber='{$order['apnumber']}' AND apcatnum='{$cats['apcatnum']}'";
}