GZIP compression in PHP

Question

Hi! I have a php script that backup my table in .sql format and I want to save the file in gzip format using PHP. How can I do that.

Answer 1

Use the Zlib functions.

Read the documentation for details

An example taken straight from the linked page:

<?php

$filename = tempnam('/tmp', 'zlibtest') . '.gz';
$s = "Only a test, test, test, test, test, test, test, test!\n";

/***** WRITING THE FILE *****/
// open file for writing with maximum compression
$zp = gzopen($filename, "w9");

// write string to file
gzwrite($zp, $s);

// close file
gzclose($zp);

/***** READING IT *****/
// open file for reading
$zp = gzopen($filename, "r");

// read 3 char
echo gzread($zp, 3);

// output until end of the file and close it.
gzpassthru($zp);
gzclose($zp);


/***** ANOTHER WAY TO READ (and print) IT *****/
// open file and print content (the 2nd time).
if (readgzfile($filename) != strlen($s)) {
        echo "Error with zlib functions!";
}
?>

Hope that helps.

Answer 2

Here is another solution which basically picks up Carlos Lima idea:

<?php
  ob_start(); /* start buffering */  
  echo "your cvs or sql output!";    
  $content = ob_get_contents(); /* get the buffer */
  ob_end_clean();
  $content = gzencode($content, 9);    
  header("Content-Type: application/force-download");
  header("Content-Type: application/octet-stream");
  header("Content-Type: application/download");
  header("Content-Description: Download SQL Export");  
  header('Content-Disposition: attachment; filename=test.txt.gz'); 
  echo $content;
  die(); 
?>

Answer 3

You can also use a filter. From the manual page:

<?php
$params = array('level' => 6, 'window' => 15, 'memory' => 9);

$original_text = "You SQL queries here...";

$fp = fopen('yourfile.sql.gz', 'w');
stream_filter_append($fp, 'zlib.deflate', STREAM_FILTER_WRITE, $params);
fwrite($fp, $original_text);
fclose($fp);
?>