The database size changed within the last few weeks.
This was due to duplicates being removed.
You will not lose any information or Functionality with the reduced MIB Size.
One observation from our installation...
We noticed that one of the MIBs we use and have written alert rules to capture traps is no longer in the database. I opened a case to get the MIB added again to the database. We incorrectly thought Orion was not sending emails for our alerts.
Other may see this as well.