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Another thing that may be worth considering is that the comments table is the second biggest in storage space, and it may be worthwhile to save space removing removing older edited versions of the "body" mediumtext entries. For example, sometimes I edit a big long post a few times to correct a few typos and this type of editing may be fairly common and may be able to reduce the database size a lot.

Yeah, great point! The body is fully duplicated on edits so that really could save some significant space.