Adjust the documentation

src/connection.rs

@@ -41,7 +41,8 @@ impl<'l> Connection<'l> {
     /// Execute a query and process the resulting rows if any.
     ///
     /// The callback is triggered for each row. If the callback returns `false`,
-    /// no more rows will be processed.
+    /// no more rows will be processed. For large queries and non-string data
+    /// types, prepared statement are highly preferable; see `prepare`.
     #[inline]
     pub fn process<F>(&self, sql: &str, callback: F) -> Result<()>
         where F: FnMut(&[(&str, Option<&str>)]) -> bool

src/statement.rs

@@ -52,7 +52,10 @@ impl<'l> Statement<'l> {
         Value::read(self, i)
     }
 
-    /// Evaluate the statement.
+    /// Evaluate the statement one step at a time.
+    ///
+    /// The function should be called multiple times until `State::Done` is
+    /// reached in order to evaluate the statement entirely.
     pub fn step(&mut self) -> Result<State> {
         match unsafe { ffi::sqlite3_step(self.raw.0) } {
             ffi::SQLITE_DONE => Ok(State::Done),