From e9ff2381bda35d706fd45f19889a05efed95e4c4 Mon Sep 17 00:00:00 2001 From: Ilya_Shlyakhter Date: Sat, 30 Nov 2019 16:51:58 +0000 Subject: [PATCH] Added a comment: same contents with different keys --- .../comment_11_9758bb3a17f63b4dcf51742ea482dbe9._comment | 8 ++++++++ 1 file changed, 8 insertions(+) create mode 100644 doc/internals/comment_11_9758bb3a17f63b4dcf51742ea482dbe9._comment diff --git a/doc/internals/comment_11_9758bb3a17f63b4dcf51742ea482dbe9._comment b/doc/internals/comment_11_9758bb3a17f63b4dcf51742ea482dbe9._comment new file mode 100644 index 0000000000..3eb9d34423 --- /dev/null +++ b/doc/internals/comment_11_9758bb3a17f63b4dcf51742ea482dbe9._comment @@ -0,0 +1,8 @@ +[[!comment format=mdwn + username="Ilya_Shlyakhter" + avatar="http://cdn.libravatar.org/avatar/1647044369aa7747829c38b9dcc84df0" + subject="same contents with different keys" + date="2019-11-30T16:51:58Z" + content=""" +@atrent -- some [[backends]] (like SHA256E) base the key not just on object contents, but also on part of its filename (the extension). So the same content can exist with two different keys. In your example, the same contents exists in one file ending with .jpg and in another ending with .56.jpeg . (This is done to give the annexed contents the same extension as the original file had before annexing, to avoid confusing some programs). There are also backends like WORM and URL, not based on checksums, that could lead to different keys with same contents. There could also be same contents added under different backends (see also [[`git-annex-migrate`|git-annex-migrate]]). Finally, there is the theoretical possibility of hash collisions. +"""]]