执行时间很短,返回0行,但并发很高导致服务器locad很高的优化 … … … … … . …

2024年 3月 15日 26.8k 0

告警主机:

告警地址:

告警时间: 2024.03.15 09:38:33

告警等级: High

告警信息: Load average is too high (per CPU load over 3 for 5m)

问题详情: Load average (1m avg):28.93

当前状态: PROBLEM:28.93

现象:

show processlist能看到有sql的线程有56个,大部分是如下的sql执行中

执行计划如下

mysql> desc select basefile0_.c_id as c_id1_23_, basefile0_.crt_time as crt_time2_23_, basefile0_.crt_user_id as crt_user3_23_, basefile0_.crt_user_name as crt_user4_23_, basefile0_.deleted as deleted5_23_, basefile0_.depart_id as depart_i6_23_, basefile0_.org_name as org_name7_23_, basefile0_.tenant_id as tenant_i8_23_, basefile0_.upd_time as upd_time9_23_, basefile0_.upd_user_id as upd_use10_23_, basefile0_.upd_user_name as upd_use11_23_, basefile0_.c_file_id as c_file_12_23_, basefile0_.c_file_name as c_file_13_23_, basefile0_.c_file_path as c_file_14_23_, basefile0_.c_file_type as c_file_15_23_, basefile0_.c_obj_id as c_obj_i16_23_, basefile0_.c_obj_type as c_obj_t17_23_, basefile0_.c_validity_date as c_valid18_23_, basefile0_.c_validity_date_start as c_valid19_23_ from t_base_file basefile0_ where basefile0_.c_obj_id='07b83a5d3fc03000' and basefile0_.c_obj_type='RETURN_BILL_ADJUNCT' and basefile0_.c_file_name='hr2024-03-15 08:53:571710464037173.jpg' and basefile0_.c_file_type=null and basefile0_.deleted=0G

*************************** 1. row ***************************

          id: 1

 select_type: SIMPLE

       table: basefile0_

  partitions: NULL

        type: ref

possible_keys: inx_id,inx_type,inx_id_type

         key: inx_id

     key_len: 1023

         ref: const

        rows: 13724

    filtered: 0.25

       Extra: Using where

1 row in set, 1 warning (0.00 sec)

explain format=json的执行计划

*************************** 1. row ***************************

EXPLAIN: {

 "query_block": {

   "select_id": 1,

   "cost_info": {

     "query_cost": "1.20"

   },

   "table": {

     "table_name": "basefile0_",

     "access_type": "ref",

     "possible_keys": [

       "inx_id"

     ],

     "key": "inx_id",

     "used_key_parts": [

       "c_obj_id"

     ],

     "key_length": "1023",

     "ref": [

       "const"

     ],

     "rows_examined_per_scan": 1,

     "rows_produced_per_join": 0,

     "filtered": "5.00",

     "cost_info": {

       "read_cost": "1.00",

       "eval_cost": "0.01",

       "prefix_cost": "1.20",

       "data_read_per_join": "370"

     },

     "used_columns": [

       "c_id",

       "crt_time",

       "crt_user_id",

       "crt_user_name",

       "deleted",

       "depart_id",

       "org_name",

       "tenant_id",

       "upd_time",

       "upd_user_id",

       "upd_user_name",

       "c_file_id",

       "c_file_name",

       "c_file_path",

       "c_file_type",

       "c_obj_id",

       "c_obj_type",

       "c_validity_date",

       "c_validity_date_start"

     ],

     "attached_condition": "((`ilp_basic_db`.`basefile0_`.`deleted` = 0) and (`ilp_basic_db`.`basefile0_`.`c_obj_type` = 'RETURN_BILL_ADJUNCT') and (`ilp_basic_db`.`basefile0_`.`c_file_name` = 'hr2024-03-15 08:53:571710464037173.jpg') and (`ilp_basic_db`.`basefile0_`.`c_file_type` = NULL))"

   }

 }

}

1 row in set, 1 warning (0.04 sec)

mysql> show index from t_base_file;

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

| Table       | Non_unique | Key_name     | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |

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

| t_base_file |          0 | PRIMARY      |            1 | c_id        | A         |    52080532 |     NULL | NULL   |      | BTREE      |         |               |

| t_base_file |          1 | inx_crt_time |            1 | crt_time    | A         |    43423464 |     NULL | NULL   | YES  | BTREE      |         |               |

| t_base_file |          1 | inx_id       |            1 | c_obj_id    | A         |    14115387 |     NULL | NULL   | YES  | BTREE      |         |               |

| t_base_file |          1 | inx_type     |            1 | c_obj_type  | A         |        3781 |     NULL | NULL   | YES  | BTREE      |         |               |

| t_base_file |          1 | inx_id_type  |            1 | c_obj_id    | A         |    17401726 |     NULL | NULL   | YES  | BTREE      |         |               |

| t_base_file |          1 | inx_id_type  |            2 | c_obj_type  | A         |    18389838 |     NULL | NULL   | YES  | BTREE      |         |               |

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

6 rows in set (0.02 sec)

查看下执行时间,不长0.37秒

mysql> select count(*)

   ->   from t_base_file basefile0_

   ->  where basefile0_.c_obj_id = '07b83a5d3fc03000'

   ->    and basefile0_.c_obj_type = 'RETURN_BILL_ADJUNCT'

   ->    and basefile0_.c_file_name = 'hr2024-03-15 08:53:571710464037173.jpg'

   ->    and basefile0_.c_file_type = null

   ->    and basefile0_.deleted = 0;

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

| count(*) |

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

|        0 |

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

1 row in set (0.37 sec)

优化思路

mysql> select count(*)  from t_base_file basefile0_  where basefile0_.c_obj_id = '0777192574802000';

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

| count(*) |

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

|    35378 |

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

1 row in set (0.33 sec)

mysql> select count(*)  from t_base_file basefile0_  where  basefile0_.c_file_type = null;

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

| count(*) |

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

|        0 |

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

1 row in set (3 min 45 sec)

mysql> select count(*)  from t_base_file basefile0_  where basefile0_.c_obj_id = '0777192574802000' and basefile0_.c_file_type = null;

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

| count(*) |

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

|        0 |

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

1 row in set (5.27 sec)

创建优化的索引

mysql> create index idx_c_file_type on t_base_file(c_file_type);

Query OK, 0 rows affected (6 min 32.54 sec)

Records: 0  Duplicates: 0  Warnings: 0

测试执行时间

mysql> select count(*)  from t_base_file basefile0_  where basefile0_.c_obj_id = '0777192574802000' and basefile0_.c_file_type = null;

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

| count(*) |

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

|        0 |

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

1 row in set (0.00 sec)

查看执行计划

mysql> desc select count(*)  from t_base_file basefile0_  where basefile0_.c_obj_id = '0777192574802000' and basefile0_.c_file_type = null;

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

| id | select_type | table | partitions | type | possible_keys | key  | key_len | ref  | rows | filtered | Extra                          |

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

|  1 | SIMPLE      | NULL  | NULL       | NULL | NULL          | NULL | NULL    | NULL | NULL |     NULL | no matching row in const table |

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

1 row in set, 1 warning (0.02 sec)

mysql> desc select count(*)  from t_base_file basefile0_ force index(inx_id) where basefile0_.c_obj_id = '0777192574802000' and basefile0_.c_file_type = null;

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

| id | select_type | table      | partitions | type | possible_keys | key    | key_len | ref   | rows  | filtered | Extra       |

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

|  1 | SIMPLE      | basefile0_ | NULL       | ref  | inx_id        | inx_id | 1023    | const | 70536 |    10.00 | Using where |

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

1 row in set, 1 warning (0.08 sec)

完整sql执行计划

mysql> desc select basefile0_.c_id as c_id1_23_, basefile0_.crt_time as crt_time2_23_, basefile0_.crt_user_id as crt_user3_23_, basefile0_.crt_user_name as crt_user4_23_, basefile0_.deleted as deleted5_23_, basefile0_.depart_id as depart_i6_23_, basefile0_.org_name as org_name7_23_, basefile0_.tenant_id as tenant_i8_23_, basefile0_.upd_time as upd_time9_23_, basefile0_.upd_user_id as upd_use10_23_, basefile0_.upd_user_name as upd_use11_23_, basefile0_.c_file_id as c_file_12_23_, basefile0_.c_file_name as c_file_13_23_, basefile0_.c_file_path as c_file_14_23_, basefile0_.c_file_type as c_file_15_23_, basefile0_.c_obj_id as c_obj_i16_23_, basefile0_.c_obj_type as c_obj_t17_23_, basefile0_.c_validity_date as c_valid18_23_, basefile0_.c_validity_date_start as c_valid19_23_ from t_base_file basefile0_ where basefile0_.c_obj_id='07b83a5d3fc03000' and basefile0_.c_obj_type='RETURN_BILL_ADJUNCT' and basefile0_.c_file_name='hr2024-03-15 08:53:571710464037173.jpg' and basefile0_.c_file_type=null and basefile0_.deleted=0G

*************************** 1. row ***************************

          id: 1

 select_type: SIMPLE

       table: NULL

  partitions: NULL

        type: NULL

possible_keys: NULL

         key: NULL

     key_len: NULL

         ref: NULL

        rows: NULL

    filtered: NULL

       Extra: no matching row in const table

1 row in set, 1 warning (0.00 sec)

explain format=json

*************************** 1. row ***************************

EXPLAIN: {

 "query_block": {

   "select_id": 1,

   "message": "no matching row in const table"

 }

}

1 row in set, 1 warning (0.09 sec)

测试完整sql的执行时间

mysql> select basefile0_.c_id as c_id1_23_, basefile0_.crt_time as crt_time2_23_, basefile0_.crt_user_id as crt_user3_23_, basefile0_.crt_user_name as crt_user4_23_, basefile0_.deleted as deleted5_23_, basefile0_.depart_id as depart_i6_23_, basefile0_.org_name as org_name7_23_, basefile0_.tenant_id as tenant_i8_23_, basefile0_.upd_time as upd_time9_23_, basefile0_.upd_user_id as upd_use10_23_, basefile0_.upd_user_name as upd_use11_23_, basefile0_.c_file_id as c_file_12_23_, basefile0_.c_file_name as c_file_13_23_, basefile0_.c_file_path as c_file_14_23_, basefile0_.c_file_type as c_file_15_23_, basefile0_.c_obj_id as c_obj_i16_23_, basefile0_.c_obj_type as c_obj_t17_23_, basefile0_.c_validity_date as c_valid18_23_, basefile0_.c_validity_date_start as c_valid19_23_ from t_base_file basefile0_ where basefile0_.c_obj_id='07b83a5d3fc03000' and basefile0_.c_obj_type='RETURN_BILL_ADJUNCT' and basefile0_.c_file_name='hr2024-03-15 08:53:571710464037173.jpg' and basefile0_.c_file_type=null and basefile0_.deleted=0;

Empty set (0.00 sec)

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