Question

So here is what I am doing.

1. Read a row each in for loop. (Because all at once is going to take some resources since I am in a shared hosting.)
   2.Get the right field data to a variable.
   3.Manipulate the req datas dependant on the extracted field.
   4.update the new fields where filed=extracted data.

Bit of addition, I am adding the current position to a file, so that the script can continue from there next time it is run.

Problem : It doesnt seem to work. The counter.txt gets values like 3-4, but it simply resides there. my db has like 1000k rows.

my code :

require ("dbconnect.php");
header("refresh:29;url=process.php"); // so it doesnt ever end. I cant use max_execution_time here for some reason.
$count = mysql_query("SELECT COUNT(*) FROM collection ");
$data = mysql_fetch_array($count);
$count = $data[0];
echo $count;

$countfile = fopen("counter.txt", "r");
$counter = fgets($countfile);
echo fgets($countfile);

while (fgets($countfile) <= $count)
 {
$i = fgets($countfile);
$takeword = mysql_query("SELECT word FROM collection WHERE id='$i'") or die();
$wd = mysql_fetch_array($takeword);
$data = $wd[0];

$d1 = hash($algorith='md2',$data);
$d2 = hash($algorith='md4',$data);



$write = mysql_query("UPDATE collection SET md2='$d1', md4='$d2' WHERE id='$i'") or die(mysql_error());

//opens, empties and write the new pointer to the file. closes, and open the file in readmode for the next read at the loop.
$counts = fopen("counter.txt", "w+");
fwrite($counts, $counter + 1);
fclose($counts);
$countfile = fopen("counter.txt", "r");
}

Any help would be appreciated 🙂 Looking for code optimization and killing the error. Suggestions would do.:)

Answer 1

Alright I’d do something like this (sorry about the delayed response, I kept forgetting)

<?php
    //main execution
    $sql = mysql_connect(...);
    if (!$sql)
        die ("No database connection");

    if (!mysql_select_db(..., $sql))
        die ("Database does not exist in this schema");

    //Run the query for this iteration.
    processQuery();
    //---

    function getQueryOffset($file)
    {
        $offset = 0; //default offset
        if (file_exists($file)) //check if the counter file exists
        {
            $contents = file_get_contents($file); //get the contents of the counter
            if ($contents !== FALSE && is_numeric($contents)) //check if an appropriate counter value
                $offset = intval($contents);
        }
        return $offset;
    }

    function processQuery()
    {
        $table = "collection"; //table to update
        $counter = "counter.txt"; //where to look for the last execution's offset.
        $maxrows = 10000; //update 10,000 rows each time this file is loaded.
        $sql = $GLOBALS['sql'];

        //calculate the number of rows in the table
        $qCount = mysql_query("SELECT COUNT(*) max FROM $table", $sql);
        $aCount = mysql_fetch_assoc($qCount);
        mysql_free_result($qCount);
        $max = $aCount["max"];

        $offset = getQueryOffset($counter); //calculate the offset (or a default 0)
        if ($offset < $max) //if offet >= max, we're done.
        {
            $qUpdate = mysql_query("SELECT word, id FROM $table LIMIT $offset, $maxrows", $sql); //get the next "maxrows" rows from the table.
            if ($qUpdate) 
            {
                $assoc = NULL;
                while (($assoc = mysql_fetch_assoc($qUpdate)) != NULL)
                {
                    $md4 = hash("md4", $assoc["word"]); //calculate the hashes
                    $md2 = hash("md2", $assoc["word"]); 
                    $id = $assoc["id"]; //id the row
                    mysql_query("UPDATE $table SET md2='$md2', md4='$md4' WHERE id=$id", $sql); //update the table columns
                }
                //update the offset in the counter file.
                file_put_contents($counter, ($offset + mysql_num_rows($qUpdate)));
                mysql_free_result($qUpdate);
            }
        }
    }

    mysql_close($sql);
?>