Kentoku Shiba (author of Spider storage engine) suggests mroonga storage engine:
Mroonga is a MySQL storage engine based on groonga, the full text search engine.
In MySQL 5.1 or later, Pluggable Storage Engine interface is introduced, and we can use custom storage engines easily. So we implement mroonga, so that we can use groonga through MySQL.
By using mroonga, you can use groonga with SQL.
Storage engine is available at: