正如我们所知 - “复杂条件的 INNER JOIN 显着增加了执行时间,请参考这个”
考虑查询
(
SELECT ...
FROM Table1
INNER JOIN Table2 ON Table1.P1 = Table2.P1 OR Table1.P2 = Table2.P2
)
在这里比较将通过“嵌套循环”完成,因此执行时间会更长,但如果我们有类似的查询 -
(
SELECT ...
FROM Table1
INNER JOIN Table2 ON Table1.P3 = Table2.P3 where Table1.P1 = "abc" OR
Table2.p2 = "xyz"
)
或类似-(SELECT ... FROM Table1 INNER JOIN Table2 ON Table1.P3 = Table2.P3 where Table1.P1 LIKE "abc" OR Table2.p2 LIKE "xyz")
比较是否也将仅通过嵌套循环进行(对于 P1 和 P2 列)?