Full-text search index in History.sqlite is never populated

Fixed in 2.3.0

You're right: History.sqlite contained a full-text search table (clips_fts) that was never populated. It was a leftover from an earlier design. ClipBook doesn't use it. Search runs against the clipboard items directly, so search results were never affected by the table being empty. I will removed it. Starting with the next update, the table is no longer created, and it's dropped automatically from existing databases on first launch. Your history isn't touched.