You are correct but it is still depends on how you setup data retention. If you want a yearly report then you should set it up to
1. Detailed Statistics retention
2. Hourly Statistics retention
3. Daily Statistics retention
4. Events Retention
I think the docs are pretty straight forward on this topic and it is easy to edit these settings. Just ensure you consider the ramifications of your settings on your DB and balance that with requirements, detail of information needed for requirements, etc...
if you have to have raw, "unrolled" up data for a year, your DB will get very large...
thank you for the idea but what i really want to know is
Example I keep track of switch monitoring data per minutes , after 3 month NPM took average of the per minutes data and only store per hour data into database .I want to know where to change these setting .
if my questions are not clear pls tell me which area that I should look into .