我希望减少在视图中查询数据的时间。
我的表格有以下结构：
表Rings包含单个响铃，每个响铃都具有ID_RingType和Number的唯一组合，但也包含ID，在其他位置用作外键。
-- RINGS
CREATE TABLE `Rings` (
ID INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
ID_RingType CHAR(2) NOT NULL,
Number MEDIUMINT UNSIGNED NOT NULL,
ID_RingStatus TINYINT DEFAULT 1,
ID_User INT(11),
DateLastChange TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
FOREIGN KEY (ID_RingType) REFERENCES RingType(Code),
FOREIGN KEY (ID_RingStatus) REFERENCES RingStatus(ID),
FOREIGN KEY (ID_User) REFERENCES `848-cso`.`Users`(UID)
);
-- create index on tripple ID_User, ID_RingType, Number
CREATE INDEX idx_rings ON `Rings` (ID_User, ID_RingType, Number);
CREATE INDEX idx_rings_overview ON `Rings` (ID_RingType, Number, ID_RingStatus);
CREATE INDEX idx_rings_numbers ON `Rings` (ID_RingStatus, ID_User, ID_RingType, Number);
响铃状态仅包含4个值及其含义
-- RING STATUS
CREATE TABLE `RingStatus` (
ID TINYINT NOT NULL PRIMARY KEY,
Name VARCHAR(20) UNIQUE COLLATE utf8_czech_ci,
NameEng VARCHAR(20)
);
响铃类型由两个字母代码
标识-- RING TYPE
CREATE TABLE `RingType` (
Code CHAR(2) NOT NULL PRIMARY KEY,
Material VARCHAR(30) COLLATE utf8_czech_ci,
Radius DOUBLE UNSIGNED,
MaxVal MEDIUMINT UNSIGNED NOT NULL
);
此外，我使用以下功能：
/*
Function returns tinyint(1) specifying, whether ring was assigned
*/
CREATE FUNCTION fn_isRingAssigned (idRingStatus TINYINT)
RETURNS TINYINT(1) DETERMINISTIC
RETURN IF(idRingStatus = 1,1,2);
我尝试优化的查询存储在以下VIEW：
/*
View finds contiguous ranges of rings grouped by type, radius and status
*/
ALTER VIEW vw_rings_overview AS SELECT
a.ID_RingType,
rt.Radius,
fn_isRingAssigned(a.ID_RingStatus) AS status,
rs.Name,
a.Number AS min,
MIN(b.Number) AS max
FROM
RingStatus AS rs, Rings AS a
JOIN RingType AS rt ON a.ID_RingType = rt.Code
JOIN Rings AS b
ON a.ID_RingType = b.ID_RingType
AND fn_isRingAssigned(a.ID_RingStatus) = fn_isRingAssigned(b.ID_RingStatus)
AND a.Number <= b.Number
WHERE NOT EXISTS
( SELECT 1
FROM Rings AS c
WHERE c.ID_RingType = a.ID_RingType
AND fn_isRingAssigned(c.ID_RingStatus) = fn_isRingAssigned(a.ID_RingStatus)
AND c.Number = a.Number - 1
)
AND NOT EXISTS
( SELECT 1
FROM Rings AS d
WHERE d.ID_RingType = b.ID_RingType
AND fn_isRingAssigned(d.ID_RingStatus) = fn_isRingAssigned(b.ID_RingStatus)
AND d.Number = b.Number + 1
)
AND fn_isRingAssigned(a.ID_RingStatus) = rs.ID
GROUP BY
a.ID_RingType,
fn_isRingAssigned(a.ID_RingStatus),
a.Number
ORDER BY
a.ID_RingType,
a.Number;
Rings表中的数据如下所示
+----+-------------+--------+---------------+---------+---------------------+
| ID | ID_RingType | Number | ID_RingStatus | ID_User | DateLastChange |
+----+-------------+--------+---------------+---------+---------------------+
| 1 | A | 1 | 4 | 2 | 2015-12-02 19:02:50 |
| 2 | A | 2 | 4 | 2 | 2015-12-02 19:02:56 |
| 3 | A | 3 | 4 | 2 | 2015-12-02 19:22:29 |
| 4 | A | 4 | 4 | 2 | 2015-12-21 20:32:24 |
| 5 | A | 5 | 4 | 2 | 2015-12-21 20:52:08 |
| 6 | A | 6 | 4 | 2 | 2015-12-21 20:52:22 |
| 7 | A | 7 | 1 | 2 | 2015-12-02 19:00:23 |
| 8 | A | 8 | 1 | 2 | 2015-12-02 19:00:23 |
| 9 | A | 9 | 1 | 2 | 2015-12-02 19:00:23 |
| 10 | A | 10 | 1 | 2 | 2015-12-02 19:00:23 |
+----+-------------+--------+---------------+---------+---------------------+
查询结果如下：
mysql> select * from vw_rings_overview;
+-------------+--------+--------+----------------+-----+-------+
| ID_RingType | Radius | status | Name | min | max |
+-------------+--------+--------+----------------+-----+-------+
| A | 20 | 2 | Assigned | 1 | 6 |
| A | 20 | 1 | Not assigned | 7 | 10 |
+-------------+--------+--------+----------------+-------------+
视图的作用是在环中找到连续的范围，具有相同的环类型，状态和半径。
表Rings目前包含少于30 000行，查询大约需要3 000行。 2秒。它预计包含数百万行，所以我希望优化表，索引和视图的设计。
以下是EXPLAIN：
mysql> explain select * from vw_rings_overview;
+----+--------------------+------------+--------+--------------------+--------------------+---------+-----------------------------+-------+-----------------------------------------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+--------------------+------------+--------+--------------------+--------------------+---------+-----------------------------+-------+-----------------------------------------------------------+
| 1 | PRIMARY | <derived2> | ALL | NULL | NULL | NULL | NULL | 19 | |
| 2 | DERIVED | a | index | idx_rings_overview | idx_rings_overview | 7 | NULL | 25173 | Using where; Using index; Using temporary; Using filesort |
| 2 | DERIVED | rt | eq_ref | PRIMARY | PRIMARY | 2 | 848-avi2.a.ID_RingType | 1 | |
| 2 | DERIVED | rs | eq_ref | PRIMARY | PRIMARY | 1 | func | 1 | Using where |
| 2 | DERIVED | b | ref | idx_rings_overview | idx_rings_overview | 2 | 848-avi2.rt.Code | 1573 | Using where; Using index |
| 4 | DEPENDENT SUBQUERY | d | ref | idx_rings_overview | idx_rings_overview | 5 | 848-avi2.b.ID_RingType,func | 1 | Using where; Using index |
| 3 | DEPENDENT SUBQUERY | c | ref | idx_rings_overview | idx_rings_overview | 5 | 848-avi2.a.ID_RingType,func | 1 | Using where; Using index |
+----+--------------------+------------+--------+--------------------+--------------------+---------+-----------------------------+-------+-----------------------------------------------------------+
以下是一些示例数据：http://sqlfiddle.com/#!9/b8b489/1