-Every function here should accomplish the follwing things:
- - Easy debugging. Every handled query gets dumped via LXDebug, if specified there.
- - Safe value binding. Although DBI is far from perfect in terms of binding, the rest of the bindings should happen here.
- - Error handling. Should a query fail, an error message will be generated here instead of in the backend code invoking DBUtils.
+=back
+
+=head1 PITFALLS AND CAVEATS
+
+=head2 Locking
+
+As mentioned above, there are two sources of database handles in the program:
+C<<$::form->get_standard_dbh>> and C<<SL::DB::Object->new->db->dbh>>. It's easy
+to produce deadlocks when using both of them. To reduce the likelyhood of
+locks, try to obey these rules:
+
+=over 4
+
+=item *
+
+In a controller that uses Rose objects, never use C<get_standard_dbh>.
+
+=item *
+
+In backend code, that has no preference, always accept the database handle as a
+parameter from the controller.
+
+=back
+
+=head2 Exports
+
+C<DBUtils> is one of the last modules in the program to use C<@EXPORT> instead
+of C<@EXPORT_OK>. This means it will flood your namespace with its functions,
+causing potential clashes. When writing new code, always either export nothing
+and call directly:
+
+ use SL::DBUtils ();
+ DBUtils::selectall_hashref_query(...)
+
+or export only what you need:
+
+ use SL::DBUtils qw(selectall_hashref_query);
+ selectall_hashref_query(...)