keywords.key_id is too small
 

Since keywords.key_id is only a tinyint it will hit the end at 8.4 million. All entries after that will fail and autoincrement returns a 0 which puts many key_id=0 entries for the same spider_id which should be prevented with a composite unique constraint on spider_id/key_id.

To fix the key_id problem it should be made a bitint instead.