
Facebook doesn't delete photos when removed, seems to keep them indefinitely - andreyf
http://photos-a.ak.fbcdn.net/hphotos-ak-snc1/hs102.snc1/5013_96426961157_709851157_2130600_2272342_n.jpg
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aristus
I'll look into what's happening, but in general it's expensive / complicated
to delete from edge-caching CDNs.

If there is a photo that gets constant traffic, the edge caches will do their
job of keeping it around. Poking around the Googles, it looks like this URL
has been reposted a lot, which creates a self-fulfilling prophecy and will
keep it around in cache.

[http://www.google.com/search?q=5013_96426961157_709851157_21...](http://www.google.com/search?q=5013_96426961157_709851157_2130600_2272342_n.jpg&hl=en&start=40&sa=N&filter=0)

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nfnaaron
So you can't _delete_ delete a picture if other people, who don't own it, like
to look at it?

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aristus
It's more complicated than that and I'm talking and about edge caches in
general here, not for my employer. I once saw a Flickr employee (Cal
Henderson?) pluck the original Ludicorp logo out of Yahoo's edge caches.
That's not to mention ISP caches and proxies, third party image search, etc,
that neither you, I, Akamai, nor Facebook control. I'll look into it and see
what's going on in this case.

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pasbesoin
I recall reading that the way the images are stored (for efficiency's sake)
makes their deletion difficult. This analogy may not be all that correct, but
I think of them as part of an archive in a fashion where their removal means
rewriting part if not all of the much larger archive.

This is probably too simplistic, but the information caused me to wonder
whether it would be practical to overwrite them in-place with equivalently
sized data that represent a pure white or black image containing no metadata
(EXIF, etc.). Data traces might be left, e.g. file name, perhaps some indexing
(are metadata indexed?), but the image itself would essentially be gone.

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Rhapso
[http://sphotos.ak.fbcdn.net/hphotos-ak-
ash1/hs343.ash1/29302...](http://sphotos.ak.fbcdn.net/hphotos-ak-
ash1/hs343.ash1/29302_402323907715_512377715_4145109_6943900_n.jpg) (this
picture is to make a point, but it was just uploaded to FB then deleted, I
think this guy has a point)

~~~
miri
Hm, wasn't Facebook launched in 2004?

~~~
Rhapso
Exactly. I can put whatever date I want onto an image, thus we should view the
duration here with skepticism, but this does appear to be an issue
nonetheless.

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mvelie
Facebook has talked about this before in their tech blogs or presentations,
mentioning it was too expensive to actually run deletes the way they store
things; and that it was actually "cheaper" and easier to just keep going and
not look back.

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coderdude
It's probably because of how they store image data.
<http://www.facebook.com/note.php?note_id=76191543919>

