一个不可思议的MySQL慢查分析与解决

( 0.00 sec)

-- 萌芽biz_date + status+ limit

-- 关键点：rows: 490319 ;

mysql > select count(*) from testtable WHERE biz_date <= '2017-08-21 00:00:00' and status =2 ;

+----------+

| count(*) |

+----------+

| 0 |

+----------+

1 row in set ( 0.34 sec)

mysql > select count(*) from testtable WHERE biz_date <= '2017-08-21 00:00:00' ;

+----------+

| count(*) |

+----------+

| 970183 |

+----------+

1 row in set ( 0.33 sec)

mysql > select count(*)from testtable;

+----------+

| count(*) |

+----------+

| 991421 |

+----------+

1 row in set ( 0.19 sec)

mysql > select distinct biz_status from whwtestbuffer;

+------------+

| biz_status | +-

-----------+

| 1 |

| 2 |

| 4 |

+------------+

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