redundant_keys.index_name='PRIMARY', '', redundant_keys.index_name) > IF(dominant_keys.index_name='PRIMARY', '', dominant_keys.index_name) ) ) ) OR (  /* Non-unique prefix columns */ LOCATE(CONCAT(redundant_keys.index_columns, ','), dominant_keys.index_columns) = 1 AND redundant_keys.non_unique = 1 ) OR (  /* Unique prefix columns */ LOCATE(CONCAT(dominant_keys.index_columns, ','), redundant_keys.index_columns) = 1 AND dominant_keys.non_unique = 0 ) );