Extensions
Scalar Functions
```sql
UINTEGER ST_Hilbert (col0 DOUBLE, col1 DOUBLE, col2 BOX_2D)
UINTEGER ST_Hilbert (col0 GEOMETRY, col1 BOX_2D)
UINTEGER ST_Hilbert (col0 BOX_2D, col1 BOX_2D)
UINTEGER ST_Hilbert (col0 BOX_2DF, col1 BOX_2DF)
UINTEGER ST_Hilbert (col0 GEOMETRY)
```