The following helped me:
mysql> truncate search_dataset;
Query OK, 0 rows affected (0.04 sec)
mysql> truncate search_index;
Query OK, 0 rows affected (0.13 sec)
mysql> truncate search_node_links;
Query OK, 0 rows affected (0.05 sec)
mysql> truncate search_total;
Query OK, 0 rows affected (0.01 sec)
Plus ./admin/settings/search/wipe
mysqldump -c --add-drop-database --character-sets-dir=utf8 --default-character-set=utf8 meinedb > mein.sql mysql --character-sets-dir=utf8 --default-character-set=utf8 meinedb < mein.sql