What Time is it: When Changed != Modified
Recently, a program specialist approached me with questions about the file modified dates in ArcCatalog. I started by explaining the Modified column in ArcCatalog shows when the data or schema was last changed in a shapefile or feature class; well, a feature class in a file geodatabase at least. The user wasn't buying it, so I set out to show him what I meant.
I can't recall if Modified has been an option in the Contents window all along or if it was added sometime along the way, but I do know it isn't turned on by default. Since I don't use it much, I had to go enable it:
I don't like demoing on real data for several reasons, including the fact the data can sometimes be the problem, so I whipped up an empty shapefile and feature class for testing. As you can see, the shapefile was created and last modified the other day. Let's use ArcPy and an InsertCursor to put a record into the shapefile and check the Modified date.
After refreshing the Contents window, we can see the Modified date gets updated after the edit session is ended using the stopEditing command. That seems pretty reasonable, i.e., the changes are committed after the editing is complete and the Modified column is updated to reflect the time the edit session ended. Let's do the same thing with a feature class.
That's odd. After ending the edit session and refreshing the Contents window, ArcCatalog is still showing the feature class as being modified when it was created a few days ago. Maybe it is my code or something is messed up with this ArcCatalog session. I am going to close out of ArcCatalog and start over.
This is even more odd. The Modified column now shows 4 minutes before the edit session ended. In fact, the Modified column shows a time that is prior to starting my edit session (the timestamps for starting the session aren't given above, but the edit session was started less than a minute before I ended it).
If the Modified column isn't showing the start or end of an edit session, what is it showing with feature classes? The answer, when ArcCatalog or ArcMap is closed. I have checked in ArcMap with manual edit sessions, and the behavior is the same. Yes, the Modified column for feature classes doesn't show when data is updated like with shapefiles but when the application is closed. In our organization with casual GIS users and disconnected Citrix sessions, the discrepancy can be days.