CODEWITHSUNDEEP
phpperformancefopenfwrite
Tim
Tim

Reputation: 31

Efficiency of fopen() with 'a' option in PHP

If I write fopen($myfile, 'a'), and $myfile is a very large file, will the server have to read the entire file in order to return the pointer to the end of the file? Or does it quickly find the pointer to the end of the file and then return that?

On a related note, when I then use fwrite() I assume it doesn't overwrite the whole file, right? It just appends stuff?

I'm basically trying to figure out whether fopen() with the 'a' option, and fwrite() are O(1) or O(n), where n is the length of the prexisting file.

Upvotes: 3

Views: 1697

Answers (3)

mario
mario

Reputation: 145482

(Related)
Note that you can also use file_put_contents instead of fopen/fwrite/fclose for appending to files - if you are that much concerned about speed:

file_put_contents($filename, $data, FILE_APPEND);

This is a bit more atomic, and does not necessitate locking.

Upvotes: 3

Matti Virkkunen
Matti Virkkunen

Reputation: 65126

The actual complexity depends on the complexity of the underlying filesystem, but PHP itself will not loop or read through the entire file, it will seek to the end and start writing from there. When opening a file in append more, it will not be erased by fwrite (you could easily try this to see how it works).

Upvotes: 4

DarkDust
DarkDust

Reputation: 92326

No, fopen does not need to read the whole file just to jump to the end. A simple seek is all that is needed.

Upvotes: 1

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