Upgrading databases

Sorry if this is in the wrong list, but this is the closest I could find...

 

I have a 8.2.4 database and I installed 8.3.7 and tried using the same /pgsql/data/base directory and got an error about incompatiblity.

 

The database currently has billions of records but it's sparsely populated.  It took about 4 months to just populate the original database and I REALLY don't want to do that again.

 

Is there a conversion routine to change the files themselves? I know I can dump and reload - but that takes large disk space and time.  Any other way around?

 

Thanks,

Mark