My revisions database/table is huge - 5 times the size of my posts table. If I empty it, will that affect the current posts?
I couldn't find an answer in forums or documentation or anywhere, so I did a test, which answers my own question, and hopefully yours too:
Using phpMyAdmin (accessed via my host's cPanel):
1. I deleted one post's revisions, and the post remained intact as expected.
2. I emptied the wp_post_revisions table - no problems resulted.
3. I didn't need to empty wp_post_revision_ids - it wasn't a large file, but I didn't need a record of how many revisions I had made to posts, so I emptied it too - no problems resulted.