[kh99]

I'm not a mysql expert, but I think you'd want to add an index to the post table on column ipaddress. If you have phpMyAdmin, you can click on the database then the post table, then "structure". Find the "+index" link and click it, then where it says "Create an index on 1 columns", press go. Then enter a name (like ipaddress), select INDEX from the dropdown, and ipaddress from the other dropdown.

If you want to do it via a query, I think it would be

CREATE INDEX ipaddress ON post (ipaddress)

Note, you really shouldn't modify the database directly if you're not sure what you're doing, and you should have a backup in case something goes wrong.

I also should mention that I'm not sure what effect adding that index will have, because of course any index takes up storage space and has to be maintained which means that every time anyone posts it has to update that index. I suppose posting happens much less often than displaying posts, so maybe it's not an issue.