""inoffensive_2006"" ...

>> 2) Do you commit each update or (whole) batch?
>
> The transaction is started. A SELECT is run for each
> row's key and user's full name columns, these are placed in
> an STL vector and sorted, and the gap between each row's
> sort order is calclated. All of the indexes for the table
> are altered to inactive, the updates of the sort order are
> run on each row. All of the indexes are altered back to
> active, and the transaction is committed.

Any DDL in Firebird performed on commit. Therefore you
run your updates with _active_ indices.

Regards,
Vlad