My wp_postmeta table is huge, around 1.2 million entries, about half of those are caused by bs entries (_bs_via_rel_2, _bs_review_verdict, _bs_source_url_2, _bs_source_url_3... etc). From what little I could see 99% of these entries are empty. Also while I do have the better adds plugin I'm currently running only one Ad on my frontpage and nothing else.
How could I clean up my wp_postmeta table from these empty entries, is this expected behavior for better ads? Also for reference I have 20.000 posts on the page.