RRDtool force the step parameter when xporting data

Question

I'm using a javascript library to visualize rrdtool data and using rrdtool xport to retreive the data from the rrd files.

Today I noticed the following: When viewing the data from now-1day: there is a datapoint of 100
but when viewing the data from now-31day, the datapoint of 100 is nowhere to be seen...

How can I make sure I get all datapoints within the specified time when using xport?
I'm using --step 10, but it didn't make a difference. No matter what --step I set it doesn't get used. I read this is because it is ignored if it's less than 1 pixel, so what's the suggested solution to this problem?

Additional info:
I'm using Collectdtool with default RRDtool plugin options: http://collectd.org/documentation/manpages/collectd.conf.5.shtml#plugin_rrdtool

Edit: Seems its the essence of RRDtool to have several archives for one month, one day, one year etc, so it makes sense that I can't get every single datapoint for the archive for one month?

Answer 1

The number of data points also depends on the available data ... so if your high-resolution RRA only covers 30 days (for example) you would get data from a lower resolution RRA once you request data for more than 30 days.