You're probably referring to one of Rob Cole's plugins. I believe his history plugin accessed the catalog database directly using SQL. As discussed in this recent thread, the plugin needs to do a song-and-dance routine to access the catalog: exit LR, run a script to access the catalog with SQL, restart LR.
Of course, accessing the catalog directly with SQL is not at all documented or supported by Adobe, so you have to do your own reverse engineering of the database schema for each new release.
thanks for your information and your guess is right regarding Rob Cole and his missing plugin. I have seen the conversation and it seems to be that there is now other way beside the reengineering path.
I have started already and it looks like the SQLite file is not a real issue (by now). My plan is to use C# to access the file and to avoid the usage of lua completely.
The first queries are functional and the most relevant tables are identified. The access works, which is quite satisfying for me. Nevertheless this was the easy part. Next challenge will be to tie the things together and find all foreign keys in the relevant tables.
Unfortunately I am not a community guy and maybe I will bring it not to a final success (time is limited), but I try to give some information back.
What I have done so far:
- access to the lrcat file throught C# with this tutorial: Getting started with SQLite in C# – Tigran's Blog
- root folders for images -> table "AgLibraryRootFolder"
- image files on the disk -> table "AgLibraryFile" -> folder seems to be the foreign key from AgLibraryRootFolder
- images in the catalog -> table "Adobe_images" -> rootfile seems to be the foreign key from AgLibraryFile
- history steps for all images -> table "Adobe_libraryImageDevelopHistoryStep" -> image seems to be the foreign key from Adobe_images
All quite interesting, but working directly on a database beside an application is always risky.
Let me know, if you are interested in more details or the progress. Normally I will not extend a topic in forums and this forum is not on my regular visit list.
Thanks to you John for the fast response.
If you learn enough of the database schema to access the history, I think it would be useful to post the schema back here. Over the years others have asked how to access the history.