Hint: No, it isn't that each one of them has more than 4 million users.
It is the way in which they use their indexing engine, their catalog.
What's funny, is that XnViewMP has already the catalog exposed in Tools | Settings | Cache Maintenance...
However:
- We need the catalog in a separate Catalog Window (eg. a menu entry in View | Catalog...) in order to be more accessible for common users.
- We need the catalog in a tree form in order to see more clearly the space occupied / number of fies for each branch and to remove more intuitively the entire branch by pressing the 'Remove' button. (implementation details upon request)
- We need a way to quick search in this catalog! A simple edit box which will issue a SQL like Select FolderID, Folder from Paths where Folder like "%foo%"; thing which will instantly (real time) find any directory which contains 'foo' inside. This is very very very important: we will have a real-time search over our folders without the need of having Windows Indexing Service kicking in now and then. Also if we're geeks we would implement also here the same AutoComplete engine described here: http://newsgroup.xnview.com/viewtopic.p ... 83#p112840 (Details upon request).
- This Catalog Window should have as root the name of the database because in the future (who knows?
) we can have multiple data stores / Catalogs. See how ASP does it:- This Catalog Window should provide the possibility to be called as a function from the Pick Folder Buttons (the [...] Buttons next to Edit boxes) in order to enter a folder in some fields. Useful at least in the new Real-Time Duplicate Search engine: http://newsgroup.xnview.com/viewtopic.php?f=60&t=28396
- The possibility to detect and relocate missing folders (right click 'Relocate...' etc.). A crucial feature. When a folder is deleted/moved/renamed outside of XnViewMP to provide a simple way to detect if the folder is missing and to relocate it manually. Mind you, now if a cataloged folder with stars, colors, keywords etc. is renamed/moved outside of XnViewMP the entire work is lost because the user simply cannot access it from inside of XnView! (details on request)
- The possibility of finding and relocate automatically the moved/renamed folders. Eg. the folders from thumb USB drivers, external disks etc. There is a simple trick which can be used in order to solve this. No, it isn't the disk's serial number/label because this solution doesn't cover the case in which one moves the c:\foo\blah to d:\bar\baz. (details upon request)
...as you see in the ASP example above - and the same thing is present in Lr, Picasa, IDImager & Photo Supreme - the Catalog is so important that they have it in a pane in the main form (usually located in the place in which we have the Categories Tree). However I think that having an always-open Catalog can lead to slowdowns since the program must update in parallel this pane.
Questions? Comments?
will jump in with a bunch of links on the theme. 
