Jiný přístup by byl -
SELECT housing_id
FROM mytable
WHERE facility_id IN (4,7)
GROUP BY housing_id
HAVING COUNT(DISTINCT facility_id) = 2
AKTUALIZOVAT - inspirován komentářem od Josvic jsem se rozhodl udělat další testování a myslel jsem, že zahrnu své poznatky.
Jednou z výhod použití tohoto dotazu je, že jej lze snadno upravit tak, aby zahrnoval více facility_id. Pokud chcete najít všechna housing_ids, která mají facility_ids 1, 3, 4 a 7, stačí to udělat -
SELECT housing_id
FROM mytable
WHERE facility_id IN (1,3,4,7)
GROUP BY housing_id
HAVING COUNT(DISTINCT facility_id) = 4
Výkon všech tří těchto dotazů se značně liší v závislosti na použité strategii indexování. Nepodařilo se mi dosáhnout přiměřeného výkonu na mé testovací datové sadě ze závislé verze poddotazu bez ohledu na použité indexování.
Řešení s vlastním spojením, které poskytuje Tim, funguje velmi dobře vzhledem k samostatným indexům jednoho sloupce ve dvou sloupcích, ale nevede si tak dobře, jak se zvyšuje počet kritérií.
Zde jsou některé základní statistiky v mé testovací tabulce – 500 000 řádků – 147963 housing_ids s potenciálními hodnotami pro facility_id mezi 1 a 9.
Zde jsou indexy používané pro spuštění všech těchto testů -
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 |
+---------+------------+---------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+
První testovaný dotaz je závislý poddotaz -
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 |
+----+--------------------+---------+-----------------+----------------------------------------------------------------+---------------------+---------+------------+--------+---------------------------------------+
Další je moje verze pomocí 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 |
+----+-------------+---------+-------+---------------------------------+-------------+---------+------+--------+------------------------------------------+
A v neposlední řadě vlastní připojení -
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 |
+----+-------------+-------+--------+----------------------------------------------------------------+---------------------+---------+-------------------------+-------+--------------------------+