However, even using parallelism, a full load may still take too
long. Most commercial utilities (e.g., RedBrick Table
Management Utility) use incremental loading during refresh
to reduce the volume of data that has to be incorporated into
the warehouse. Only the updated tuples are inserted.
However, the load process now is harder to manage. The
incremental load conflicts with ongoing queries, so it is
treated as a sequence of shorter transactions (which commit
periodically, e.g., after every 1000 records or every few
seconds), but now this sequence of transactions has to becoordinated to ensure consistency of derived data and indices
with the base data.