Batch processing should give more context

I'm testing the Migration API with a large dataset as well and have to query the DB quite often to determine if the migration is still running or not. For a migration process that can take hours to complete (url aliases, users, nodes...), I'd indeed be super useful to have some visual progress showing where we are with the migration, at least periodically.

Here are some numbers for the migration I've played with:

mysql> SELECT COUNT(nid) FROM node;
+------------+
| COUNT(nid) |
+------------+
|       3805 |
+------------+
1 row in set (0.00 sec)

mysql> SELECT COUNT(uid) FROM users;
+------------+
| COUNT(uid) |
+------------+
|     179699 |
+------------+
1 row in set (0.23 sec)

mysql> SELECT COUNT(pid) FROM url_alias;
+------------+
| COUNT(pid) |
+------------+
|     182959 |
+------------+
1 row in set (0.26 sec))

Worked as a charm but took ages to complete always.