使用 MySql View 的问题 - 非常慢，但为什么呢？

Question

我在使用 mysql 视图时遇到了一个大问题。 我正在生成一个视图，在该视图中我加入了几个表以接收我真正需要的信息。

我有以下看法：

CREATE OR REPLACE VIEW view_test AS

SELECT nve_nr.nve_nvenr AS collonr,
CONCAT (adr_emp.adr_name1, "\n", adr_emp.adr_name2, "\n", adr_emp.adr_strasse, "\n", adr_emp.adr_land , " -     ", adr_emp.adr_plz, " ", adr_emp.adr_ort) AS emp_adr,

UNIX_TIMESTAMP((SELECT MAX(t_1.colst_timestamp) FROM tbl_collo_status t_1 WHERE t_1.colst_nve_id = 
nve_nr.nve_id AND t_1.colst_status_code IN (10, 11, 76))) AS status_x,

UNIX_TIMESTAMP((SELECT MAX(t_2.colst_timestamp) FROM tbl_collo_status t_2 WHERE t_2.colst_nve_id = 
nve_nr.nve_id AND t_2.colst_status_code IN (20,25,91))) AS status_y,

UNIX_TIMESTAMP((SELECT MAX(t_3.colst_timestamp) FROM tbl_collo_status t_3 WHERE t_3.colst_nve_id = 
nve_nr.nve_id AND t_3.colst_status_code IN (30,99,104))) AS status_z,

TIME_TO_SEC(TIMEDIFF((SELECT MAX(t_2.colst_timestamp) FROM tbl_collo_status t_2 WHERE t_2.colst_nve_id = 
nve_nr.nve_id AND t_2.colst_status_code IN (20,25,91)), (SELECT MAX(t_1.colst_timestamp) FROM tbl_collo_status t_1 
WHERE t_1.colst_nve_id = nve_nr.nve_id AND t_1.colst_status_code IN (10, 11, 76)))) AS timediff_xy,

TIME_TO_SEC(TIMEDIFF((SELECT MAX(t_3.colst_timestamp) FROM tbl_collo_status t_3 WHERE t_3.colst_nve_id = 
nve_nr.nve_id AND t_3.colst_status_code IN (30,99,104)), (SELECT MAX(t_2.colst_timestamp) FROM tbl_collo_status t_2 
WHERE t_2.colst_nve_id = nve_nr.nve_id AND t_2.colst_status_code IN (20,25,91)))) AS timediff_yz,

TIME_TO_SEC(TIMEDIFF((SELECT MAX(t_3.colst_timestamp) FROM tbl_collo_status t_3 WHERE t_3.colst_nve_id = 
nve_nr.nve_id AND t_3.colst_status_code IN (30,99,104)), (SELECT MAX(t_1.colst_timestamp) FROM tbl_collo_status t_1 
WHERE t_1.colst_nve_id = nve_nr.nve_id AND t_1.colst_status_code IN (10, 11, 76)))) AS timediff_xz,

CAST(SUBSTR(nve_nr.nve_nvenr, 1, 3) AS UNSIGNED INTEGER) AS filter_collonr,

(SELECT t_5.colst_status_code FROM tbl_collo_status t_5 WHERE t_5.colst_nve_id=nve_nr.nve_id ORDER BY 
t_5.colst_timestamp DESC LIMIT 1) AS filter_last_status,

sdg.sdg_kunde AS filter_kunden_id,

sdg.sdg_id AS filter_sdg_id,

nve_nr.nve_id AS filter_nve_id,

adr_emp.adr_id AS filter_adr_emp_id

FROM ((tbl_nve_nr nve_nr LEFT JOIN tbl_sendungen sdg ON nve_nr.nve_sdg_id = sdg.sdg_id)

LEFT JOIN tbl_adressen adr_emp ON adr_emp.adr_id = sdg.sdg_adr2_id);

现在我在该视图中有超过 250.000 个数据集，如果我在该视图上开始选择，我将需要 20 多分钟才能收到结果。 解释选择将返回以下内容：

//![解释从视图中选择][1]

我不能在没有 10 个声望的情况下发布图片，所以我会这样尝试：

谁能告诉我我可以做些什么来加快查看速度？ 在不使用视图的情况下执行查询大约需要 2 分钟，并且应该从 250.000 个可用数据集中选择 25 个数据集的限制。

//编辑： 所以我用另一种方式解决了这个问题:) 下面描述的解决方案不能使 SQL-Query 工作得足够快，所以我通过以下方式解决了：

删除视图，因为不再需要它们， 更改表 nve_nr 为最后状态和时间戳添加两个字段。 如果时间戳比现有时间戳更新，则在 collo_status 上创建一个触发器来替换该值。 -> 减少一个子查询 - 速度从 2 分钟缩短到近 60 秒。

重建索引并直接在php中运行查询 -> 更多的 php 代码，但更胖 - 现在加速到近 13 秒 :)

使用新字段更新数据库包括查找当前最新状态的过程。

所以新的查询是这样的：

SELECT SQL_CALC_FOUND_ROWS 
sdg.sdg_lieferschein AS referenz, 
nve_nr.nve_nvenr AS collonr, 
nve_nr.nve_last_timestamp AS filter_status_time, 
nve_nr.nve_last_status AS filter_last_status, 
sdg.sdg_kunde AS filter_kunden_id, 
sdg.sdg_id AS filter_sdg_id, 
nve_nr.nve_id AS filter_nve_id, 
adr_emp.adr_id AS filter_adr_emp_id, 
adr_emp.adr_name1 AS emp_adr_name1, 
adr_emp.adr_name2 AS emp_adr_name2, 
adr_emp.adr_land AS emp_adr_land, 
adr_emp.adr_plz AS emp_adr_plz, 
adr_emp.adr_ort AS emp_adr_ort,
UNIX_TIMESTAMP(t_1.colst_timestamp) AS status_x, 
t_1.colst_status_code AS status_code_x, 
UNIX_TIMESTAMP(t_2.colst_timestamp) AS status_y, 
t_2.colst_status_code AS status_code_y, 
UNIX_TIMESTAMP(t_3.colst_timestamp) AS status_z, 
t_3.colst_status_code AS status_code_z, 
TIME_TO_SEC(TIMEDIFF(t_2.colst_timestamp, t_1.colst_timestamp)) AS timediff_xy, 
TIME_TO_SEC(TIMEDIFF(t_3.colst_timestamp, t_2.colst_timestamp)) AS timediff_yz, 
TIME_TO_SEC(TIMEDIFF(t_3.colst_timestamp, t_1.colst_timestamp)) AS timediff_xz, 
CAST(SUBSTR(nve_nr.nve_nvenr, 1, 3) AS UNSIGNED INTEGER) AS filter_collonr 
FROM tbl_nve_nr nve_nr 
LEFT JOIN tbl_sendungen sdg 
ON nve_nr.nve_sdg_id = sdg.sdg_id 
LEFT JOIN tbl_adressen adr_emp 
ON (adr_emp.adr_id = sdg.sdg_adr2_id) 
LEFT JOIN tbl_collo_status t_1 
ON (t_1.colst_nve_id = nve_nr.nve_id AND t_1.colst_aktiv = 1 AND t_1.colst_status_code IN (10, 11, 76)) 
LEFT JOIN tbl_collo_status t_2 
ON (t_2.colst_nve_id = nve_nr.nve_id AND t_2.colst_aktiv = 1 AND t_2.colst_status_code IN (20,25,91)) 
LEFT JOIN tbl_collo_status t_3 
ON (t_3.colst_nve_id = nve_nr.nve_id AND t_3.colst_aktiv = 1 AND t_3.colst_status_code IN (30,99,104)) 
GROUP BY collonr 
ORDER BY collonr DESC 
LIMIT 900, 75

//[1]：http://i.stack.imgur.com/TPw6s.png

Answer 1

主要问题可能是索引，但也很值得删除 co 相关的子查询。像这样的东西：-

CREATE OR REPLACE VIEW view_test AS

SELECT nve_nr.nve_nvenr AS collonr,
CONCAT (adr_emp.adr_name1, "\n", adr_emp.adr_name2, "\n", adr_emp.adr_strasse, "\n", adr_emp.adr_land , " -     ", adr_emp.adr_plz, " ", adr_emp.adr_ort) AS emp_adr,

UNIX_TIMESTAMP((SELECT MAX(t_1.colst_timestamp) FROM tbl_collo_status t_1 WHERE t_1.colst_nve_id = 
nve_nr.nve_id AND t_1.colst_status_code IN (10, 11, 76))) AS status_x,

UNIX_TIMESTAMP((SELECT MAX(t_2.colst_timestamp) FROM tbl_collo_status t_2 WHERE t_2.colst_nve_id = 
nve_nr.nve_id AND t_2.colst_status_code IN (20,25,91))) AS status_y,

UNIX_TIMESTAMP((SELECT MAX(t_3.colst_timestamp) FROM tbl_collo_status t_3 WHERE t_3.colst_nve_id = 
nve_nr.nve_id AND t_3.colst_status_code IN (30,99,104))) AS status_z,

TIME_TO_SEC(TIMEDIFF((SELECT MAX(t_2.colst_timestamp) FROM tbl_collo_status t_2 WHERE t_2.colst_nve_id = 
nve_nr.nve_id AND t_2.colst_status_code IN (20,25,91)), (SELECT MAX(t_1.colst_timestamp) FROM tbl_collo_status t_1 
WHERE t_1.colst_nve_id = nve_nr.nve_id AND t_1.colst_status_code IN (10, 11, 76)))) AS timediff_xy,

TIME_TO_SEC(TIMEDIFF((SELECT MAX(t_3.colst_timestamp) FROM tbl_collo_status t_3 WHERE t_3.colst_nve_id = 
nve_nr.nve_id AND t_3.colst_status_code IN (30,99,104)), (SELECT MAX(t_2.colst_timestamp) FROM tbl_collo_status t_2 
WHERE t_2.colst_nve_id = nve_nr.nve_id AND t_2.colst_status_code IN (20,25,91)))) AS timediff_yz,

TIME_TO_SEC(TIMEDIFF((SELECT MAX(t_3.colst_timestamp) FROM tbl_collo_status t_3 WHERE t_3.colst_nve_id = 
nve_nr.nve_id AND t_3.colst_status_code IN (30,99,104)), (SELECT MAX(t_1.colst_timestamp) FROM tbl_collo_status t_1 
WHERE t_1.colst_nve_id = nve_nr.nve_id AND t_1.colst_status_code IN (10, 11, 76)))) AS timediff_xz,

CAST(SUBSTR(nve_nr.nve_nvenr, 1, 3) AS UNSIGNED INTEGER) AS filter_collonr,

MAX(t_5.colst_status_code) AS filter_last_status,

sdg.sdg_kunde AS filter_kunden_id,

sdg.sdg_id AS filter_sdg_id,

nve_nr.nve_id AS filter_nve_id,

adr_emp.adr_id AS filter_adr_emp_id

FROM tbl_nve_nr nve_nr 

LEFT JOIN tbl_sendungen sdg ON nve_nr.nve_sdg_id = sdg.sdg_id

LEFT JOIN tbl_adressen adr_emp ON adr_emp.adr_id = sdg.sdg_adr2_id

INNER JOIN tbl_collo_status t_5  ON t_5.colst_nve_id = nve_nr.nve_id

GROUP BY collonr, emp_adr, status_x, status_y, status_z, timediff_xy, timediff_yz, timediff_xz, filter_collonr, filter_kunden_id, filter_sdg_id, filter_nve_id, filter_adr_emp_id

问题是您的查询有很多相关的子查询，这些子查询通常表现不佳。

最好的解决方案可能是用与其他视图（包含选择的那些视图）的连接来替换所有相关的子查询

编辑 - 拆分其他子选择：-

创建视图：-

CREATE ALGORITHM = UNDEFINED VIEW vw_MaxTimeStamp_10_11_76 AS SELECT t_1.colst_nve_id, MAX(t_1.colst_timestamp) AS MaxTimestamp FROM tbl_collo_status t_1 WHERE t_1.colst_status_code IN (10, 11, 76) GROUP BY t_1.colst_nve_id

CREATE ALGORITHM = UNDEFINED VIEW vw_MaxTimeStamp_20_25_91 AS SELECT t_1.colst_nve_id, MAX(t_1.colst_timestamp) AS MaxTimestamp FROM tbl_collo_status t_1 WHERE t_1.colst_status_code IN (20,25,91) GROUP BY t_1.colst_nve_id

CREATE ALGORITHM = UNDEFINED VIEW vw_MaxTimeStamp_30_99_104 AS SELECT t_1.colst_nve_id, MAX(t_1.colst_timestamp) AS MaxTimestamp FROM tbl_collo_status t_1 WHERE t_1.colst_status_code IN (30,99,104) GROUP BY t_1.colst_nve_id

CREATE ALGORITHM = UNDEFINED VIEW vw_MaxStatusCode AS SELECT colst_nve_id, MAX(t_5.colst_status_code) AS MaxStatusCode FROM tbl_collo_status t_5 GROUP BY colst_nve_id

然后你的主视图可以简化成这样的（怕没有测试所以可能有一些错别字）

CREATE OR REPLACE VIEW view_test AS

SELECT nve_nr.nve_nvenr AS collonr,
CONCAT (adr_emp.adr_name1, "\n", adr_emp.adr_name2, "\n", adr_emp.adr_strasse, "\n", adr_emp.adr_land , " -     ", adr_emp.adr_plz, " ", adr_emp.adr_ort) AS emp_adr,
UNIX_TIMESTAMP(vw_MaxTimeStamp_10_11_76.MaxTimestamp) AS status_x,
UNIX_TIMESTAMP(vw_MaxTimeStamp_20_25_91.MaxTimestamp) AS status_y,
UNIX_TIMESTAMP(vw_MaxTimeStamp_30_99_104.MaxTimestamp) AS status_z,
TIME_TO_SEC(TIMEDIFF(vw_MaxTimeStamp_20_25_91.MaxTimestamp, vw_MaxTimeStamp_10_11_76.MaxTimestamp)) AS timediff_xy,
TIME_TO_SEC(TIMEDIFF(vw_MaxTimeStamp_30_99_104.MaxTimestamp, vw_MaxTimeStamp_20_25_91.MaxTimestamp)) AS timediff_yz,
TIME_TO_SEC(TIMEDIFF(vw_MaxTimeStamp_30_99_104.MaxTimestamp, vw_MaxTimeStamp_10_11_76.MaxTimestamp)) AS timediff_xz,
CAST(SUBSTR(nve_nr.nve_nvenr, 1, 3) AS UNSIGNED INTEGER) AS filter_collonr,
vw_MaxStatusCode.MaxStatusCode AS filter_last_status
sdg.sdg_kunde AS filter_kunden_id,
sdg.sdg_id AS filter_sdg_id,
nve_nr.nve_id AS filter_nve_id,
adr_emp.adr_id AS filter_adr_emp_id
FROM tbl_nve_nr nve_nr 
LEFT JOIN tbl_sendungen sdg ON nve_nr.nve_sdg_id = sdg.sdg_id
LEFT JOIN tbl_adressen adr_emp ON adr_emp.adr_id = sdg.sdg_adr2_id
INNER JOIN tbl_collo_status t_5  ON t_5.colst_nve_id = nve_nr.nve_id
LEFT OUTER JOIN vw_MaxTimeStamp_10_11_76 ON vw_MaxTimeStamp_10_11_76.colst_nve_id = nve_nr.nve_id
LEFT OUTER JOIN vw_MaxTimeStamp_20_25_91 ON vw_MaxTimeStamp_20_25_91.colst_nve_id = nve_nr.nve_id
LEFT OUTER JOIN vw_MaxTimeStamp_30_99_104 ON vw_MaxTimeStamp_30_99_104.colst_nve_id = nve_nr.nve_id
LEFT OUTRER JOIN vw_MaxStatusCode ON vw_MaxStatusCode.colst_nve_id = nve_nr.nve_id