id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	db3_docallegato_acc	NULL	ref	fk_db3_docallegato_acc_db3_bollettario_acc1_idx	fk_db3_docallegato_acc_db3_bollettario_acc1_idx	8	const	1	100.00	Using where; Using index