Fig. 7.2.4 Placing large pebbles in the hourglass.The result of placing pebbles in the hourglass is that the flow of sand is interrupted and
the flow is erratic and inefficient.
In many ways, the transactions that run through an online system are like the grains of
sand. As long as the transactions are small and uniform in size, the efficiency of the
system is quite good. But when large transactions are mixed in with small transactions in
the workload of an online transaction processing system, the flow is very mixed and
inefficient.
And when the flow is inefficient, the result is poor response time.
Chapter 7.2: The Standard Work Unit