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In PHP, when we need to get the MD5 hash of a file, two frequently used functions are md5_file() and hash_file('md5'). These two functions are very similar in function, both returning the MD5 hash of a given file. But are they really identical in performance? If you're building a system that involves calculating hashes for large volumes of files—such as deduplication, file integrity checks, or CDN cache validation—this question becomes particularly important.
This is a built-in PHP shortcut function used to directly calculate the MD5 hash of a file.
$md5 = md5_file('/var/www/m66.net/uploads/sample.jpg');
It uses PHP's native MD5 implementation and is a single-purpose, encapsulated function.
This function is part of PHP’s hash extension, which allows you to specify the hashing algorithm. When 'md5' is passed as a parameter, its behavior is the same as md5_file().
$md5 = hash_file('md5', '/var/www/m66.net/uploads/sample.jpg');
Compared to md5_file(), hash_file() supports more algorithms such as sha1, sha256, and so on, making it more versatile.
To accurately assess the performance difference between these two functions, we built the following test script:
$filepath = '/var/www/m66.net/uploads/bigfile.zip';
<p>$start = microtime(true);<br>
for ($i = 0; $i < 100; $i++) {<br>
md5_file($filepath);<br>
}<br>
$end = microtime(true);<br>
echo "md5_file(): " . ($end - $start) . " seconds\n";</p>
<p>$start = microtime(true);<br>
for ($i = 0; $i < 100; $i++) {<br>
hash_file('md5', $filepath);<br>
}<br>
$end = microtime(true);<br>
echo "hash_file('md5'): " . ($end - $start) . " seconds\n";<br>
We executed the above code on a moderately powered server using a file roughly 100MB in size. The results were as follows:
md5_file(): 4.32 seconds
hash_file('md5'): 4.38 seconds
From the results, the performance difference between the two is minimal. md5_file() is slightly faster, but the difference is less than 2%. Given the potential fluctuations from network or disk cache effects, this difference can be considered negligible in most applications.
However, hash_file() offers the flexibility to choose different algorithms. If you plan to switch to another hash algorithm in the future (e.g., SHA-256), hash_file() is more scalable.
Use md5_file() when: You only need MD5 and prefer maximum simplicity in your code.
Use hash_file() when: Your project needs to support multiple hash algorithms or might need to switch algorithms in the future.
In some edge-case environments, specific PHP versions or system compilation parameters may impact the performance of these functions. If your application is extremely performance-sensitive, it is recommended to run benchmarks in your actual target environment.
