数据库查询执行时间

Question

当我使用以下方法计算行数时，总共需要 4 分 51.62 秒。

mysql> select count(*) from result where id < 1000000;
+----------+
| count(*) |
+----------+
|        0 |
+----------+
1 row in set (4 min 51.62 sec)

然而，

当我使用以下方法计算行数作为增加id时，总共需要41.05秒。

mysql> select count(*) from result where id < 500000;
+----------+
| count(*) |
+----------+
|        0 |
+----------+
1 row in set (0.14 sec)

mysql> select count(*) from result where id < 600000;
1 row in set (0.21 sec)

mysql> select count(*) from result where id < 700000;
1 row in set (0.28 sec)

mysql> select count(*) from result where id < 800000;
1 row in set (0.23 sec)

mysql> select count(*) from result where id < 900000;
1 row in set (0.26 sec)

mysql> select count(*) from result where id < 950000;
1 row in set (0.27 sec)

mysql> select count(*) from result where id < 1000000;
1 row in set (39.66 sec)

谁能给我解释一下，为什么会这样，就像batch 或cache。我不知道为什么会这样？提前致谢。

Answer 1

id 950000 to 1000000 插入多行错误