I was running postgres 8.4 on arch but now have 9 installed I want to use pg_upgrade to upgrade but I don't know what all the options I have to use are, and all the directories that I have to point it to. it asks for a previous pg binary directory... but that's gone. Will it still work? note: I've no important data, just play db's I just want to know how to do it.
I'm sure you've read the documentation but just in case you haven't - "F.32. pg_upgrade".
The step-by-step instructions are especially detailed.
As a minumum you need to provide values for
If your old installation is missing you could always (I hope so, I've never used Arch Linux) re-install it without overwriting the old data directory. If your distribution doesn't facilitate that you could re-install (temporarily) the old version from source.
Then you could run
That's one of the problems with using Postgres on Arch: upon upgrade it won't change the file format automatically.
I usually just do database dump and restore as upgrade procedure. (you should have database dumps anyway as a backup...)