Question

查询目的：MySQL查询的目的是查找事件（y.indicator = '1'）与紧接其时间戳的行之间的时间戳差异。这些错误在数据库中多次出现。

样本数据：

row_id | indicator | timestamp
----+---------+--------+----------------------------
abcdef | 0         | 1592900862 
abcdef | 0         | 1592900900 
abcdef | 1         | 1592900905 
abcdef | 1         | 1592900907
qrstuv | 0         | 1592900863 
qrstuv | 1         | 1592900867 
qrstuv | 0         | 1592900880 
qrstuv | 0         | 1592900900 
qrstuv | 1         | 1592900905

示例输出

row_id | Diff      | timestamp
----+---------+--------+----------------------------
abcdef | 5         | 1592900905 
abcdef | 2         | 1592900907
qrstuv | 4         | 1592900867 
qrstuv | 5         | 1592900805

数据库：需要UNION包含16个不同的表。这些表合起来有千万行。

查询工作，当条件AND x.row_id IN ('abcde12242fdsdsfds','safzxvdseafcz')仅包含一个row_id时，但是中断，当我添加其他row_id时（因此将在下面的示例中中断）。我将需要在20,000 row_id上运行它。

因此将其归结为两个问题：

优化：如何提高代码效率，使其可以在超过1个row_id上使用？
样式：我是否可以生成JOIN表y而不重复整个UNION语句。

SELECT x.row_id, x.timestamp, 
    MIN(x.timestamp - y.timestamp) AS Diff 
    FROM 
    (SELECT * FROM table01db.db
    UNION SELECT * FROM table02db.db
    UNION SELECT * FROM table03db.db 
    UNION SELECT * FROM table04db.db 
    UNION SELECT * FROM table05db.db 
    UNION SELECT * FROM table06db.db 
    UNION SELECT * FROM table07db.db
    UNION SELECT * FROM table08db.db 
    UNION SELECT * FROM table09db.db 
    UNION SELECT * FROM table10db.db 
    UNION SELECT * FROM table11db.db
    UNION SELECT * FROM table12db.db 
    UNION SELECT * FROM table13db.db 
    UNION SELECT * FROM table14db.db 
    UNION SELECT * FROM table15db.db 
    UNION SELECT * FROM table16db.db ) AS x
    JOIN (SELECT * FROM table01db.db
    UNION SELECT * FROM table02db.db 
    UNION SELECT * FROM table03db.db 
    UNION SELECT * FROM table04db.db
    UNION SELECT * FROM table05db.db 
    UNION SELECT * FROM table06db.db 
    UNION SELECT * FROM table07db.db 
    UNION SELECT * FROM table08db.db 
    UNION SELECT * FROM table09db.db 
    UNION SELECT * FROM table10db.db
    UNION SELECT * FROM table11db.db 
    UNION SELECT * FROM table12db.db 
    UNION SELECT * FROM table13db.db 
    UNION SELECT * FROM table14db.db 
    UNION SELECT * FROM table15db.db 
    UNION SELECT * FROM table16db.db ) AS y
    ON x.row_id = y.row_id
    WHERE x.indicator = '1' 
    AND x.timestamp > y.timestamp
    AND x.row_id IN ('abcde12242fdsdsfds','safzxvdseafcz')
    GROUP BY x.row_id, x.timestamp

MySQL SELECT，UNION，JOIN查询优化

0 个答案: