Друг подход би бил -
SELECT housing_id
FROM mytable
WHERE facility_id IN (4,7)
GROUP BY housing_id
HAVING COUNT(DISTINCT facility_id) = 2
АКТУАЛИЗИРАНЕ - вдъхновен от коментара на Йосвич, реших да направя още тестове и реших, че ще включа моите констатации.
Едно от предимствата на използването на тази заявка е, че е лесно да се модифицира, за да включи повече facility_ids. Ако искате да намерите всички жилища_идентификатори, които имат идентификатори на съоръжение 1, 3, 4 и 7, просто го направете -
SELECT housing_id
FROM mytable
WHERE facility_id IN (1,3,4,7)
GROUP BY housing_id
HAVING COUNT(DISTINCT facility_id) = 4
Производителността и на трите от тези заявки варира значително в зависимост от използваната стратегия за индексиране. Не успях да получа разумна производителност на моя набор от тестови данни от зависимата версия на подзаявката, независимо от използваното индексиране.
Решението за самостоятелно свързване, предоставено от Tim, се представя много добре при дадени отделни индекси на една колона за двете колони, но не се представя толкова добре, тъй като броят на критериите се увеличава.
Ето някои основни статистически данни в моята тестова таблица - 500 000 реда - 147963 жилища_ids с потенциални стойности за facility_id между 1 и 9.
Ето индексите, използвани за провеждане на всички тези тестове -
SHOW INDEXES FROM mytable;
+---------+------------+---------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type |
+---------+------------+---------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+
| mytable | 0 | UQ_housing_facility | 1 | housing_id | A | 500537 | NULL | NULL | | BTREE |
| mytable | 0 | UQ_housing_facility | 2 | facility_id | A | 500537 | NULL | NULL | | BTREE |
| mytable | 0 | UQ_facility_housing | 1 | facility_id | A | 12 | NULL | NULL | | BTREE |
| mytable | 0 | UQ_facility_housing | 2 | housing_id | A | 500537 | NULL | NULL | | BTREE |
| mytable | 1 | IX_housing | 1 | housing_id | A | 500537 | NULL | NULL | | BTREE |
| mytable | 1 | IX_facility | 1 | facility_id | A | 12 | NULL | NULL | | BTREE |
+---------+------------+---------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+
Първата тествана заявка е зависимата подзаявка -
SELECT SQL_NO_CACHE DISTINCT housing_id
FROM mytable
WHERE housing_id IN (SELECT housing_id FROM mytable WHERE facility_id=4)
AND housing_id IN (SELECT housing_id FROM mytable WHERE facility_id=7);
17321 rows in set (9.15 sec)
+----+--------------------+---------+-----------------+----------------------------------------------------------------+---------------------+---------+------------+--------+---------------------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+--------------------+---------+-----------------+----------------------------------------------------------------+---------------------+---------+------------+--------+---------------------------------------+
| 1 | PRIMARY | mytable | range | NULL | IX_housing | 4 | NULL | 500538 | Using where; Using index for group-by |
| 3 | DEPENDENT SUBQUERY | mytable | unique_subquery | UQ_housing_facility,UQ_facility_housing,IX_housing,IX_facility | UQ_housing_facility | 8 | func,const | 1 | Using index; Using where |
| 2 | DEPENDENT SUBQUERY | mytable | unique_subquery | UQ_housing_facility,UQ_facility_housing,IX_housing,IX_facility | UQ_housing_facility | 8 | func,const | 1 | Using index; Using where |
+----+--------------------+---------+-----------------+----------------------------------------------------------------+---------------------+---------+------------+--------+---------------------------------------+
SELECT SQL_NO_CACHE DISTINCT housing_id
FROM mytable
WHERE housing_id IN (SELECT housing_id FROM mytable WHERE facility_id=1)
AND housing_id IN (SELECT housing_id FROM mytable WHERE facility_id=3)
AND housing_id IN (SELECT housing_id FROM mytable WHERE facility_id=4)
AND housing_id IN (SELECT housing_id FROM mytable WHERE facility_id=7);
567 rows in set (9.30 sec)
+----+--------------------+---------+-----------------+----------------------------------------------------------------+---------------------+---------+------------+--------+---------------------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+--------------------+---------+-----------------+----------------------------------------------------------------+---------------------+---------+------------+--------+---------------------------------------+
| 1 | PRIMARY | mytable | range | NULL | IX_housing | 4 | NULL | 500538 | Using where; Using index for group-by |
| 5 | DEPENDENT SUBQUERY | mytable | unique_subquery | UQ_housing_facility,UQ_facility_housing,IX_housing,IX_facility | UQ_housing_facility | 8 | func,const | 1 | Using index; Using where |
| 4 | DEPENDENT SUBQUERY | mytable | unique_subquery | UQ_housing_facility,UQ_facility_housing,IX_housing,IX_facility | UQ_housing_facility | 8 | func,const | 1 | Using index; Using where |
| 3 | DEPENDENT SUBQUERY | mytable | unique_subquery | UQ_housing_facility,UQ_facility_housing,IX_housing,IX_facility | UQ_housing_facility | 8 | func,const | 1 | Using index; Using where |
| 2 | DEPENDENT SUBQUERY | mytable | unique_subquery | UQ_housing_facility,UQ_facility_housing,IX_housing,IX_facility | UQ_housing_facility | 8 | func,const | 1 | Using index; Using where |
+----+--------------------+---------+-----------------+----------------------------------------------------------------+---------------------+---------+------------+--------+---------------------------------------+
Следва моята версия, използваща GROUP BY ... HAVING COUNT ...
SELECT SQL_NO_CACHE housing_id
FROM mytable
WHERE facility_id IN (4,7)
GROUP BY housing_id
HAVING COUNT(DISTINCT facility_id) = 2;
17321 rows in set (0.79 sec)
+----+-------------+---------+-------+---------------------------------+-------------+---------+------+--------+------------------------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+---------+-------+---------------------------------+-------------+---------+------+--------+------------------------------------------+
| 1 | SIMPLE | mytable | range | UQ_facility_housing,IX_facility | IX_facility | 4 | NULL | 198646 | Using where; Using index; Using filesort |
+----+-------------+---------+-------+---------------------------------+-------------+---------+------+--------+------------------------------------------+
SELECT SQL_NO_CACHE housing_id
FROM mytable
WHERE facility_id IN (1,3,4,7)
GROUP BY housing_id
HAVING COUNT(DISTINCT facility_id) = 4;
567 rows in set (1.25 sec)
+----+-------------+---------+-------+---------------------------------+-------------+---------+------+--------+------------------------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+---------+-------+---------------------------------+-------------+---------+------+--------+------------------------------------------+
| 1 | SIMPLE | mytable | range | UQ_facility_housing,IX_facility | IX_facility | 4 | NULL | 407160 | Using where; Using index; Using filesort |
+----+-------------+---------+-------+---------------------------------+-------------+---------+------+--------+------------------------------------------+
И не на последно място самостоятелното присъединяване -
SELECT SQL_NO_CACHE a.housing_id
FROM mytable a
INNER JOIN mytable b
ON a.housing_id = b.housing_id
WHERE a.facility_id = 4 AND b.facility_id = 7;
17321 rows in set (1.37 sec)
+----+-------------+-------+--------+----------------------------------------------------------------+---------------------+---------+-------------------------+-------+-------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+-------+--------+----------------------------------------------------------------+---------------------+---------+-------------------------+-------+-------------+
| 1 | SIMPLE | b | ref | UQ_housing_facility,UQ_facility_housing,IX_housing,IX_facility | IX_facility | 4 | const | 94598 | Using index |
| 1 | SIMPLE | a | eq_ref | UQ_housing_facility,UQ_facility_housing,IX_housing,IX_facility | UQ_housing_facility | 8 | test.b.housing_id,const | 1 | Using index |
+----+-------------+-------+--------+----------------------------------------------------------------+---------------------+---------+-------------------------+-------+-------------+
SELECT SQL_NO_CACHE a.housing_id
FROM mytable a
INNER JOIN mytable b
ON a.housing_id = b.housing_id
INNER JOIN mytable c
ON a.housing_id = c.housing_id
INNER JOIN mytable d
ON a.housing_id = d.housing_id
WHERE a.facility_id = 1
AND b.facility_id = 3
AND c.facility_id = 4
AND d.facility_id = 7;
567 rows in set (1.64 sec)
+----+-------------+-------+--------+----------------------------------------------------------------+---------------------+---------+-------------------------+-------+--------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+-------+--------+----------------------------------------------------------------+---------------------+---------+-------------------------+-------+--------------------------+
| 1 | SIMPLE | b | ref | UQ_housing_facility,UQ_facility_housing,IX_housing,IX_facility | IX_facility | 4 | const | 93782 | Using index |
| 1 | SIMPLE | d | eq_ref | UQ_housing_facility,UQ_facility_housing,IX_housing,IX_facility | UQ_housing_facility | 8 | test.b.housing_id,const | 1 | Using index |
| 1 | SIMPLE | c | eq_ref | UQ_housing_facility,UQ_facility_housing,IX_housing,IX_facility | UQ_housing_facility | 8 | test.b.housing_id,const | 1 | Using index |
| 1 | SIMPLE | a | eq_ref | UQ_housing_facility,UQ_facility_housing,IX_housing,IX_facility | UQ_housing_facility | 8 | test.d.housing_id,const | 1 | Using where; Using index |
+----+-------------+-------+--------+----------------------------------------------------------------+---------------------+---------+-------------------------+-------+--------------------------+
