What file format/database format does Picasa use?

I am trying to figure out what file format the .db file and .pmp files are. I tried using db_dump (Berkeley DB) for the .db files, but it seems that they are not Berkeley DB, or of an older version. I have no idea what the .PMP files are.

Directory of C:\Users\me\AppData\Local\Google\Picasa2\db3
 6/09/2010  08:07 PM           303,748 imagedata_uid64.pmp
 1/18/2010  10:34 PM             4,885 imagedata_unification_lhlist.pmp
 6/09/2010  10:55 PM           155,752 imagedata_width.pmp
 6/09/2010  10:55 PM     1,286,346,614 previews_0.db
 6/10/2010  10:06 AM           467,168 previews_index.db

Any help appreciated.

.PMP is a format proprietory to Picasa, used to store informations about images. ( Reference )

( Note: Below referenced blog post is dated, not sure how relevant/correct it is to the current version of Picasa )

More info:

in the db2 directory there are a number of files. The important files for this are albumdata_token.pmp, albumdata_uid.pmp and albumdata_name.pmp

Here are the contents of the files:

albumdata_name.pmp -

this is the name of the albums in picasa. The first two are defaults and are not included in any of the other files.

Starred Photos

Screensaver 

root

modified_for_tags

sam3 

Sample Pictures 

Sammy

albumdata_uid.pmp - This is where the hashes are.

b131d7e17dfdff73eb0340b4e9d3d6f3

8e92a45a6abed421488a5774ec3f4a4c 

ca05c73419475ade037f8df528849c91

ec9771e026e3ce55c468354abcfce4ee

c332f1814ff6d4f21dbb41b41149544d

albumdata_token.pmp

Here's we see the uid applied to create a token for the albums. Note that "star" and "screensaver" do not have uids.

]star

]screensaver

]album:b131d7e17dfdff73eb0340b4e9d3d6f3

]album:8e92a45a6abed421488a5774ec3f4a4c

]album:ca05c73419475ade037f8df528849c91

]album:ec9771e026e3ce55c468354abcfce4ee

]album:c332f1814ff6d4f21dbb41b41149544d 

Now, if we look at the lastalbumselected value in the registry, we can pair it up to the hash since these files are all listed in the same order. If you exclude star and screensaver you can see that the lastalbumselected for me was sam3.

You can even go one step further if you include albumdata_filename.pmp. This file also matches up to the other files, except I forgot to mention one thing. "root" is literally the root of the logical drive that picasa searched(in this case C:), so it is excluded from albumdata_filename.pmp. This file contains the path to where the images are stored.

Other files to pay attention to:

bigthumbs.db 

thumbs2.db

thumbs.db

previews.db

These all follow the good old thumbs.db structure and contain thumbnails of all of the images at various resolutions, since picasa can send files directly to photo processing businesses.

One other thing that is of pretty vital importance in terms of proving that someone created an album and that the program didn't just index something.

In the Picasa2Albums directory you'll see a file for each of the album(s) created by the user under the folder using the DBID as its name. Below are the contents of the album I created stored in a file named {c332f1814ff6d4f21dbb41b41149544d.pal.

'picasa2album>

'dbid>0164eaeacdd4046f5c1e44522fe44527

'albumid>c332f1814ff6d4f21dbb41b41149544d

'property name="uid" type="string" value="c332f1814ff6d4f21dbb41b41149544d">

'property name="category" type="num" value="0"> 

'property name="date" type="real64" value="39272.630035"

'property name="token" type="string" value="]album:c332f1814ff6d4f21dbb41b41149544d"

'property name="name" type="string" value="Sammy"

'files>

'filename>[C]\sam3\sam1.jpg

'filename>[C]\sam3\sam3.jpg

'filename>[C]\sam3\sam2.jpg

'filename>[C]\sam3\DSCF1890.JPG

'/files> 

'/property>

'/picasa2album>

I added an answer on Stackoverflow to a similar question about .pmp files, which also points to some partial notes I wrote about the format of these files.