Generally speaking the Aperture Library is pretty rock solid, you shouldn’t have any troubles with it. But as a database, sometimes (especially when there’s a program crash while Aperture is doing something important) you’ll launch and get an error about your database. Luckily Aperture 3 has three built-in tools for dealing with this (while Aperture 2 only had two tools).
To bring up the program’s First Aid tools, restart Aperture holding down the Command andOption keys. at the same time.
REPAIR PERMISSIONS, REPAIR DATABASE, REBUILD DATABASE
The three choices for database troubleshooting are Repair Permission, Repair Database, andRebuild Database. We’re not going to belabor the description of each as this long dialog box already describes each but here’s our general guide to the process.
Repair Permissions - This basically fixes permissions issues in the database, which is a very low-level repair. Generally if you’re seeing weirdness in your Library, this is not going to do much. If you’ve just moved your Library from one machine to another, start here though.
Repair Database – This used to be the highest level of database repair Aperture had to offer. This scans the whole database for issues and fixes anything it finds. It’s more thorough but more time intensive.
Rebuild Database - This is a very long process (relative to the other two) but the most complete. Aperture re-indexes every single image (not just ones where it finds a problem.) Go to this one when nothing else seems to be working.