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mysql8.0.16 Slow query
Posted by: 东山 邢
Date: August 03, 2021 10:44PM

Querying both conditions is very slow.But two criteria alone are fast.
mysql> select count(1) from meteorological_data where create_time between '2021-07-28 00:00:00' and '2021-08-04 00:00:00' ;
+----------+
| count(1) |
+----------+
| 101627 |
+----------+
1 row in set (0.07 sec)

mysql> select count(1) from meteorological_data where equipment_no = 1000000195;
+----------+
| count(1) |
+----------+
| 45817 |
+----------+
1 row in set (0.08 sec)

mysql> select count(1) from meteorological_data where equipment_no = 1000000195 and create_time between '2021-07-28 00:00:00' and '2021-08-04 00:00:00';
+----------+
| count(1) |
+----------+
| 14 |
+----------+
1 row in set (19.71 sec)


What causes the pattern to be narrow?

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