Database bloating

I have a site which has been actively selling products for a few years now. I’ve been having problems with the site dropping offline with my host stating I have 2 tables in the database over 100,000 rows (actually _postmeta is 323,957 rows) which are taking too long for the server to retrieve.

Seems _postmeta and _woocommerce_order_itemmeta are the culprits. I could easily jump into mySQl and delete those excess rows but am not sure if that’s a safe thing to do. You see, I’m not a developer but just a dad helping out his son with a website.

The database most likely has tons of old post revisions sitting out there and other junk that could easily be deleted but am not sure what can go and what to keep.

Any thoughts short of hiring a developer (then I would have to trust them) to clean this up? I am running a new plugin “Advanced Database Cleaner” which seemed to help but did nothing to delete the un-needed rows of data in the tables referenced above.

Any advice would be appreciated.

Thanks