Polylines stored in a Spatialite database through ArcGIS Desktop do not appear store true curves. Any curves in the lines are densified into straight segments and vertices.
To test this I created a circle in a file-geodatabase (FGDB) feature class. I then copied this feature class into my Spatialite DB. To verify that the copy normally copied curves, I also copied the feature class into another file-geodatabase and a personal geodatabase (PGDB).
While the circle kept its curve in the feature class copied to the second FGDB and the PGDB, it did not keep the curve in Spatialite.
FGDB circle:
PGDB circle:
Spatialite circle:
To show vertices for the Spatialite feature class I needed to copy the feature class back into my FGDB, so I also wanted to test the Spatialite data directly.
This answer to How to identify "true arcs" in Arcmap? includes a python snippet to quickly check whether a feature contains true curves - here are my results:
FGDBMaster
You have true curves!
Spatialite
No curves here
PGDB
You have true curves!
FGDB
You have true curves!
Now I understand that this doesn't signal that Spatialite doesn't support true curves at all, or that other GIS applications can't do it, it just shows that the Spatialite support in ArcGIS Desktop doesn't appear to support true curves but instead densifies them.
