The SPD Engine has several
new features that enhance I/O performance. These features can dramatically
increase the performance of I/O bound applications, in which large
amounts of data must be delivered to the application for processing.
Multiple Directory Paths
You can specify multiple directory paths and devices
for each component type because the SPD Engine can reference multiple
physical files across volumes as a single logical file. For very large
data sets, this feature circumvents any file size limits that the
operating system might impose.
Physical Separation of the Data File and the Associated Indexes
Because each component file type can be stored in a
different location, file dependencies are not a concern when deciding
where to store the component files. Only cost, performance, and availability
of disk space need to be considered.
WHERE Optimization
The SPD Engine automatically determines the optimal process to use
to evaluate observations for qualifying criteria specified in a WHERE
statement. WHERE statement efficiency depends on such factors as
whether the variables in the expression are indexed. A WHERE evaluation
planner is included in the SPD Engine that can choose the best method
to use to evaluate WHERE expressions that use indexes to optimize
evaluation.