I'm having the same issue. I had a raster catalog which I deleted.
I have used a script to populate a "Raster" column to an external source of tifs. My file geodatabase was 27.5 G before I compacted it and its still 21.16. This is way too large. What other options do I have? Is it because I mapped a path to a raster for 6,000 features? Though that doesn't seem logical as the rasters are external to the database. Any help would appreciated before I have to can all this work.
In ArcCatalog:
1) Right click on your file geodatabase.
2) Choose "Compact" from the menu.
Compact did not work on my same problem. Raster dataset of 100 or so jp2s has a 12gb .gdbtable file. Total size of folder outside of gdb is a little over 1gb. Any other suggestions? Thanks
Same exact issue randomly popped up (ten years later) and apparently this is still the only solution. Compressing the GDB didn't have any effect.