The number you enter as the Read Block Size defines the number of records fetched by the component during a single simulation step. You set the Write Block Size to define the number of records to be written. Most Data Provider components possess a Read Block Size property; most of the Data Sink components offer to customize the Write Block Size. Transformation components like the Staging component offer to customize values for both reading and writing.
The Block Size property is evaluated during both project
simulation and project execution. A small number might be suitable
for simulation purposes, but will slow down execution time when
you click Execute. In simulation the Block Size is restricted to
32K.
