informatica faq's 1

The following pages summarize some of the questions that typically arise during development and suggest potential resolutions.

Q: How does source format affect performance? (i.e., is it more efficient to source from a flat file rather than a database?)
In general, a flat file that is located on the server machine loads faster than a database located on the server machine. Fixed-width files are faster than delimited files because delimited files require extra parsing. However, if there is an intent to perform intricate transformations before loading to target, it may be advisable to first load the flat file into a relational database, which allows the PowerCenter mappings to access the data in an optimized fashion by using filters and custom SQL SELECTs where appropriate.


Q: What are some considerations when designing the mapping? (i.e. what is the impact of having multiple targets populated by a single map?)
With PowerCenter, it is possible to design a mapping with multiple targets. You can then load the targets in a specific order using Target Load Ordering. The recommendation is to limit the amount of complex logic in a mapping. Not only is it easier to debug a mapping with a limited number of objects, but they can also be run concurrently and make use of more system resources. When using multiple output files (targets), consider writing to multiple disks or file systems simultaneously. This minimizes disk seeks and applies to a session writing to multiple targets, and to multiple sessions running simultaneously.