The SPD Engine has several 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 best method 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. It can choose the best method to use to optimize
evaluation of WHERE expressions that use indexes.