LIKE clause really slow. LIKE clause really slow.
Visitors are able to search books by subject, author and title.
Note that there are 30,000 Joins are really quite efficient in mysql. Yeah, that sounds right. There have been discussions here in the last two months on this topic. The keyword-table solution would let you index individual words, with a pointer to the book. Also keyword-index descriptions in blobs in this table, if you like.