PHP preg_replace datetimes with increased values

Question

I need to find and replace, within a potentially big SQL dump file (~2-3MB), all date occurrences with their actual value increased with a given value. This is needed as my company uses this SQL dump file to deploy demos of a particular software, and the dates need to be translated to correctly fit the period the demo will be usable.

This is a small extract to serve as an example:

INSERT INTO ordini (id, id_fornitore, data, oggetti_ordine, data_consegna, controllo, data_consegna_prevista, resp_controllo, DDT, nr_DDT, iknow_iddocu, spedizione, pagamento) VALUES (10, 204, '2011-11-29', 'Palline gialle##Palline rosse##Palline verdi##§§1000##200##360##§§12 €##10 €##11.5 €##', '2012-12-29', 0, '2011-12-05', 0, '', '', 0, 'A mano', '30 gg.'), (13, 204, '2011-11-30', 'Palline verdi##§§12##§§5.750##', '2013-04-23', 0, '1970-01-01', 0, '', '', 0, '', ''), (14, 204, '2011-11-30', 'Palline verdi##Palline rosse##§§12##22##§§5.750##5.750##', '2013-02-22', 0, '2011-12-31', 0, '', '', 0, 'A mano', 'Ri.Ba. 30 gg.');

As you can see, all the dates within the file are in mysql YYYY-MM-DD DATETIME format, like: '2013-03-12'. Occasionally, some of them may include the time as well after the date, but being this irrelevant to my needs, times should be left unchanged.

I eventually arranged this simple script:

<?php
$push_period = "30";

print "<h1>Parsing file...</h1>";
print "<h2>Pushing dates ahead of {$push_period} days.</h2>";

$file=implode("\n",file('db.sql'));
print($file);

preg_match_all('@(\d\d\d\d)-(\d\d)-(\d\d)@', $file, $match, PREG_OFFSET_CAPTURE);

print "<br /><br />";

print "<table border=1 align='center'>";
print "<th colspan='3'><b>Dates moved {$push_period} days ahead</b></th>";

$array_new_dates = array();

foreach ($match[0] as $occurrence) {

    print "<tr><td>";
    print "<pre>";
    print_r($occurrence);
    print "</pre>";
    print "</td><td width='40' align='center'>";
    print "=>";
    print "</td><td>";
    print "<pre>";

    $temp_array = array();
    $modified_value = date('Y-m-d', strtotime($occurrence[0] . " +".$push_period." days"));
    $temp_array[0] = $modified_value;
    $temp_array[1] = $occurrence[1];
    $array_new_dates[] = $temp_array;
    print_r($temp_array);
    print "</pre>";
    print "</td></tr>";

    $file = substr_replace($file, $modified_value, $occurrence[1], 10);
}

print "</table>";

print($file);
$file = str_replace("\n", "", $file);

$fp=fopen('updated_db.sql','w');

// Dumping updated file
fwrite($fp,$file,strlen($file));
?>

Now, my problem is that if I run this script with large files, I am predictably prompted this error:

Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 64 bytes) in /srv/www/htdocs/mysoftware_dev/date_replacer.php on line 10

I hence need to elaborate the input in steps. Problem is, if I split the input file in fixed-size blocks, I might happen to trunk a date (and consequently not pushing it ahead of the needed value). What would a good approach to this problem be? (apart from manually pre-splitting the input file into several smaller files). Thank you for any help.

Answer 1

This can be much simpler with a preg_replace_callback() call, which allows you to use a callback function to do logic on your match:

$string = ''; // Data from file

$string = preg_replace_callback(
    '/\d{4}-\d{2}-\d{2}/',
    function($matches) {
        $date = new DateTime(reset($matches));
        $oneDay = new DateInterval('P1D');
        $date->add($oneDay);
        return $date->format('Y-m-d');
    },
    $string
);

Notice how I tweaked your Regex, and used {} to specify how many digits and removed the capturing groups. We use PHP's DateTime class, and then ::add() a DateInterval to the value, before returning the date with our original ::format().

I'd also take @NietTheDarkAbsol's advice and take a look at fgets() if you still have memory issues. However, my cleaned up logic will reduce memory usage (since you won't be storing all of the matches in a variable and looping through them one by one).

Answer 2

I suppose that you will use this script on request, not on daily base. Maybe the easiest solution is to increase your memory limit whitch is currently on 128MB.

I didn't try if your script really works what it should, but try to increase memory limit with this in PHP script:

ini_set("memory_limit","512M");

or with this in php.ini:

memory_limit = 512M

Also take a look at this