</pre>
It may be surprising to see [[Database Module|db:create]] on the bottom of this list. This has to do with the semantics of updating queries: all expressions can only be evaluated on databases that have been created before running the query.
If an inconsistency is found, an error message is returned and all accessed databases remain untouched (atomicity). For the user, this means that updates are only visible '''after''' the end of a snapshot.