User`s guide

CHAPTER 4 Projects and Jobs
User’s Guide 35
Partial execution or initialization during simulation
It is extremely time consuming to start the entire simulation after making
modifications to a single component, especially when working with a large
amount of input records in a project that consists of dozens of components. On
the other hand, it can be frustrating to single step through a large project when
you are only interested in simulating a component somewhere in the middle of
a complex simulation flow. The commands
Step through and Initialize through
provide an effective way of multi-stepping a project to your point of interest.
Simulating up to a certain component
To validate your current project by starting from a component somewhere in
the middle of a project, select the component, and then select Start Through
from the Run menu. The simulation starts the current project, processes all
components between the current and the selected component, and finally
processes the selected component.
Impact of Read/Write Block Size
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.
Note 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.
Controlling multiple data streams
While most projects will consist of a single stream of components connected
through links, it is technically possible to have multiple, not interconnected
data streams within a single project. Since Sybase IQ ETL is a parallel system,
there is no way to predict in which order the streams are processed.