以下SQL语句，执行时间，有时快，有时慢。※在Navicat Premium标签窗口中执行信息如下。您有什么建议吗？
SELECT
device.xmbh AS xmbh,
IFNULL(COUNT(*),0) AS alarmCount
FROM
t_gj_device_alarm device
INNER JOIN
t_sb_register_info info
ON info.xmbh = device.xmbh --number
AND info.device_no = device.device_no --device number
AND info.delete_flag = '0' --delete flag
WHERE device.delete_flag = '0' --delete flag
AND (device.gjjb = 'SPSBWXH' OR device.gjjb = 'SPSBHMBD' ) --Query some device
AND device.gjsj >= '2019-03-04' --start day（one year）
AND device.gjsj <= '2020-03-11' --end day（one year）
GROUP BY device.xmbh
ORDER BY null
执行时间：2.6s〜6.166s结果：1415
数据量：
SELECT count(*) FROM t_gj_device_alarm
result:365027
SELECT count(*) from t_sb_register_info
result:8560
select count(*)/(SELECT count(*) FROM t_gj_device_alarm WHERE delete_flag = 0) as rate
from t_gj_device_alarm device
WHERE
(device.gjjb = 'SPSBWXH' OR device.gjjb = 'SPSBHMBD' )
AND device.gjsj >= '2019-03-04'
AND device.gjsj <= '2020-03-11'
and device.delete_flag = 0
result:0.6448
索引信息在下面：
table:t_gj_device_alarm
name column type indexMethod sortRule base
xmbh_device xmbh, device_no, delete_flag, gjjb NORMAL BTREE A 25090
xmbh_time xmbh, gjsj, delete_flag NORMAL BTREE A 376363
index1 gjsj, gjjb, delete_flag, device_no, xmbh NORMAL BTREE A 376363
index3 gjjb, xmbh, gjsj NORMAL BTREE A 376363
index2 device_no, xmbh, gjsj NORMAL BTREE A 376363
table:t_sb_register_info
name column type indexMethod sortRule base
index1 xmbh, device_no NORMAL BTREE A 8616
index2 sblxcode, xmbh, device_no NORMAL BTREE A 8616
执行计划如下：
id select_type table type possible_keys key key_len ref rows filtered extra
1 SIMPLE info ALL PRIMARY,index1 8616 100 Using where; Using temporary
1 SIMPLE device ref xmbh_device,xmbh_time,index1,index3,index2 xmbh_device 305 zhgd_2.0.info.xmbh,zhgd_2.0.info.device_no,const 16 100 Using index condition; Using where
个人资料（长时间执行一次）
select state,sum(duration) as total_r,round(100*sum(duration)/(select sum(duration) from information_schema.profiling where query_id = 17),2) as pct_r,count(*) as calls,sum(duration)/count(*) as "R/Call" from information_schema.profiling where query_id = 17 group by state order by total_r desc;
state total_r pct_r calls R/Call
Sending data 5.698915 99.77 1 5.698915
statistics 0.012113 0.21 1 0.012113
end 0.000229 0 2 0.0001145
starting 0.00017 0 1 0.00017
removing tmp table 0.000116 0 1 0.000116
preparing 0.000107 0 1 0.000107
checking permissions 0.000096 0 2 0.000048
Creating tmp table 0.000084 0 1 0.000084
init 0.000076 0 1 0.000076
freeing items 0.000066 0 1 0.000066
query end 0.000063 0 1 0.000063
closing tables 0.000058 0 1 0.000058
cleaning up 0.000056 0 1 0.000056
optimizing 0.000051 0 1 0.000051
Opening tables 0.00005 0 1 0.00005
executing 0.000038 0 1 0.000038
System lock 0.000037 0 1 0.000037
variable_name:(One time in a long Execution time)
Created_tmp_disk_tables 0
Created_tmp_files 0
Created_tmp_tables 9
Handler_commit 1
Handler_delete 0
Handler_discover 0
Handler_external_lock 4
Handler_mrr_init 0
Handler_prepare 0
Handler_read_first 1
Handler_read_key 213549
Handler_read_last 0
Handler_read_next 208637
Handler_read_prev 0
Handler_read_rnd 74
Handler_read_rnd_next 11041
Handler_rollback 0
Handler_savepoint 0
Handler_savepoint_rollback 0
Handler_update 204064
Handler_write 2471
profiles (One time in a short Execution time)
state total_r pct_r calls R/Call
Sending data 2.311715 99.87 1 2.311715
statistics 0.002046 0.09 1 0.002046
end 0.000186 0.01 2 0.000093
starting 0.000166 0.01 1 0.000166
checking permissions 0.000079 0 2 0.0000395
removing tmp table 0.000078 0 1 0.000078
init 0.000059 0 1 0.000059
preparing 0.000054 0 1 0.000054
Creating tmp table 0.000052 0 1 0.000052
Opening tables 0.000048 0 1 0.000048
freeing items 0.000042 0 1 0.000042
closing tables 0.00004 0 1 0.00004
optimizing 0.000038 0 1 0.000038
cleaning up 0.000035 0 1 0.000035
System lock 0.000031 0 1 0.000031
executing 0.000031 0 1 0.000031
query end 0.000028 0 1 0.000028
variable_name:(One time in a short Execution time)
Created_tmp_disk_tables 0
Created_tmp_files 2
Created_tmp_tables 9
Handler_commit 1
Handler_delete 0
Handler_discover 0
Handler_external_lock 4
Handler_mrr_init 0
Handler_prepare 0
Handler_read_first 1
Handler_read_key 213464
Handler_read_last 0
Handler_read_next 208637
Handler_read_prev 0
Handler_read_rnd 65
Handler_read_rnd_next 10889
Handler_rollback 0
Handler_savepoint 0
Handler_savepoint_rollback 0
Handler_update 203988
Handler_write 2319
更新：表创建SQL如下：
SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;
-- ----------------------------
-- Table structure for t_gj_device_alarm
-- ----------------------------
DROP TABLE IF EXISTS `t_gj_device_alarm`;
CREATE TABLE `t_gj_device_alarm` (
`alarm_no` varchar(40) CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL DEFAULT '' COMMENT '',
`xmbh` varchar(50) CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL DEFAULT '' COMMENT '',
`device_no` varchar(50) CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL DEFAULT '' COMMENT '',
`gjsj` datetime(0) NOT NULL COMMENT '',
`gjjb` varchar(100) CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL DEFAULT '' COMMENT '',
`photofilepath` varchar(200) CHARACTER SET utf8 COLLATE utf8_unicode_ci DEFAULT '' COMMENT '',
`audiofilepath` varchar(200) CHARACTER SET utf8 COLLATE utf8_unicode_ci DEFAULT '' COMMENT '',
`send_msg` tinyint(4) NOT NULL DEFAULT 0 COMMENT '',
`is_read` tinyint(4) NOT NULL DEFAULT 0 COMMENT '',
`delete_flag` tinyint(4) NOT NULL DEFAULT 0 COMMENT '',
`create_time` datetime(0) NOT NULL COMMENT '',
`create_user` varchar(20) CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL DEFAULT '' COMMENT '',
`modify_time` datetime(0) NOT NULL COMMENT '',
`modify_user` varchar(20) CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL DEFAULT '' COMMENT '',
PRIMARY KEY (`alarm_no`) USING BTREE,
INDEX `xmbh_device`(`xmbh`, `device_no`, `delete_flag`, `gjjb`) USING BTREE,
INDEX `xmbh_time`(`xmbh`, `gjsj`, `delete_flag`) USING BTREE,
INDEX `index1`(`gjsj`, `gjjb`, `delete_flag`, `device_no`, `xmbh`) USING BTREE,
INDEX `index3`(`gjjb`, `xmbh`, `gjsj`) USING BTREE,
INDEX `index2`(`device_no`, `xmbh`, `gjsj`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_unicode_ci ROW_FORMAT = Compact;
SET FOREIGN_KEY_CHECKS = 1;
SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;
-- ----------------------------
-- Table structure for t_sb_register_info
-- ----------------------------
DROP TABLE IF EXISTS `t_sb_register_info`;
CREATE TABLE `t_sb_register_info` (
`device_no` varchar(50) CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL DEFAULT '' COMMENT '',
`xmbh` varchar(50) CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL DEFAULT '' COMMENT '',
`sbbh` varchar(100) CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL DEFAULT '' COMMENT '',
`sblxcode` varchar(100) CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL DEFAULT '' COMMENT '',
`xpoint` varchar(200) CHARACTER SET utf8 COLLATE utf8_unicode_ci DEFAULT '0.000000' COMMENT '',
`ypoint` varchar(200) CHARACTER SET utf8 COLLATE utf8_unicode_ci DEFAULT '0.000000' COMMENT '',
`sbxh` varchar(100) CHARACTER SET utf8 COLLATE utf8_unicode_ci DEFAULT '' COMMENT '',
`azrq` date DEFAULT NULL COMMENT '',
`ccrq` date DEFAULT NULL COMMENT '',
`qsdw` varchar(200) CHARACTER SET utf8 COLLATE utf8_unicode_ci DEFAULT '' COMMENT '',
`wxdw` varchar(200) CHARACTER SET utf8 COLLATE utf8_unicode_ci DEFAULT '' COMMENT '',
`zrren` varchar(20) CHARACTER SET utf8 COLLATE utf8_unicode_ci DEFAULT '' COMMENT '',
`lxdh` varchar(20) CHARACTER SET utf8 COLLATE utf8_unicode_ci DEFAULT '' COMMENT '',
`lybh` varchar(100) CHARACTER SET utf8 COLLATE utf8_unicode_ci DEFAULT '' COMMENT '',
`sort` int(11) NOT NULL DEFAULT 0 COMMENT '',
`bz` varchar(500) CHARACTER SET utf8 COLLATE utf8_unicode_ci DEFAULT '' COMMENT '',
`dev_status` varchar(255) CHARACTER SET utf8 COLLATE utf8_unicode_ci DEFAULT NULL COMMENT '',
`device_name` varchar(255) CHARACTER SET utf8 COLLATE utf8_unicode_ci DEFAULT '' COMMENT '',
`delete_flag` tinyint(4) NOT NULL DEFAULT 0 COMMENT '',
`create_time` datetime(0) NOT NULL COMMENT '',
`create_user` varchar(20) CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL DEFAULT '' COMMENT '',
`modify_time` datetime(0) NOT NULL COMMENT '',
`modify_user` varchar(20) CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL DEFAULT '' COMMENT '',
PRIMARY KEY (`device_no`) USING BTREE,
INDEX `index1`(`xmbh`, `device_no`) USING BTREE,
INDEX `index2`(`sblxcode`, `xmbh`, `device_no`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_unicode_ci ROW_FORMAT = Compact;
SET FOREIGN_KEY_CHECKS = 1;
iotop捕获（一次）
Total DISK READ : 3.93 M/s | Total DISK WRITE : 144.53 K/s
Actual DISK READ: 3.93 M/s | Actual DISK WRITE: 507.82 K/s
PID PRIO USER DISK READ DISK WRITE SWAPIN IO> COMMAND
281 be/3 root 0.00 B/s 0.00 B/s 0.00 % 3.37 % [jbd2/vda1-8]
1834 be/4 mysql 527.94 K/s 1256.27 K/s 0.00 % 0.01 % mysqld --~mysql.sock
这是原因吗？
update-03 / 16
“ AND device.gjsj> ='2019-03-04'AND device.gjsj <='2020-03-11'”
{
"considered_execution_plans": [
{
"plan_prefix": [
],
"table": "`t_sb_register_info` `info`",
"best_access_path": {
"considered_access_paths": [
{
"access_type": "ref",
"index": "PRIMARY",
"usable": false,
"chosen": false
},
{
"access_type": "ref",
"index": "index1",
"usable": false,
"chosen": false
},
{
"access_type": "scan",
"rows": 8407,
"cost": 1778.4,
"chosen": true
}
]
},
"cost_for_plan": 1778.4,
"rows_for_plan": 8407,
"rest_of_plan": [
{
"plan_prefix": [
"`t_sb_register_info` `info`"
],
"table": "`t_gj_device_alarm` `device`",
"best_access_path": {
"considered_access_paths": [
{
"access_type": "ref",
"index": "xmbh_device",
"rows": 23,
"cost": 193366,
"chosen": true
},
{
"access_type": "ref",
"index": "xmbh_time",
"rows": 103,
"cost": 865942,
"chosen": false
},
{
"access_type": "ref",
"index": "index2",
"rows": 23,
"cost": 193366,
"chosen": false
},
{
"access_type": "range",
"rows": 136677,
"cost": 7.4e8,
"chosen": false
}
]
},
"cost_for_plan": 233812,
"rows_for_plan": 193361,
"chosen": true
}
]
},
{
"plan_prefix": [
],
"table": "`t_gj_device_alarm` `device`",
"best_access_path": {
"considered_access_paths": [
{
"access_type": "ref",
"index": "xmbh_device",
"rows": 2e308,
"cost": 0,
"chosen": false
},
{
"access_type": "ref",
"index": "xmbh_time",
"usable": false,
"chosen": false
},
{
"access_type": "ref",
"index": "index2",
"usable": false,
"chosen": false
},
{
"access_type": "range",
"rows": 136677,
"cost": 88081,
"chosen": true
}
]
},
"cost_for_plan": 88081,
"rows_for_plan": 136677,
"rest_of_plan": [
{
"plan_prefix": [
"`t_gj_device_alarm` `device`"
],
"table": "`t_sb_register_info` `info`",
"best_access_path": {
"considered_access_paths": [
{
"access_type": "ref",
"index": "PRIMARY",
"rows": 1,
"cost": 136677,
"chosen": true
},
{
"access_type": "ref",
"index": "index1",
"rows": 1,
"cost": 136677,
"chosen": false
},
{
"access_type": "scan",
"using_join_cache": true,
"rows": 6306,
"cost": 1.72e8,
"chosen": false
}
]
},
"cost_for_plan": 252094,
"rows_for_plan": 136677,
"pruned_by_cost": true
}
]
}
]
},
“ AND device.gjsj在'2019-03-04'和'2020-03-11'之间”
{
"considered_execution_plans": [
{
"plan_prefix": [
],
"table": "`t_sb_register_info` `info`",
"best_access_path": {
"considered_access_paths": [
{
"access_type": "ref",
"index": "PRIMARY",
"usable": false,
"chosen": false
},
{
"access_type": "ref",
"index": "index1",
"usable": false,
"chosen": false
},
{
"access_type": "scan",
"rows": 8407,
"cost": 1778.4,
"chosen": true
}
]
},
"cost_for_plan": 1778.4,
"rows_for_plan": 8407,
"rest_of_plan": [
{
"plan_prefix": [
"`t_sb_register_info` `info`"
],
"table": "`t_gj_device_alarm` `device`",
"best_access_path": {
"considered_access_paths": [
{
"access_type": "ref",
"index": "index2",
"rows": 23,
"cost": 193366,
"chosen": true
},
{
"access_type": "ref",
"index": "xmbh_device_1",
"rows": 21,
"cost": 176551,
"chosen": true
},
{
"access_type": "ref",
"index": "xmbh_time_1",
"rows": 111,
"cost": 933199,
"chosen": false
},
{
"access_type": "range",
"rows": 136677,
"cost": 7.4e8,
"chosen": false
}
]
},
"cost_for_plan": 213635,
"rows_for_plan": 176547,
"chosen": true
}
]
},
{
"plan_prefix": [
],
"table": "`t_gj_device_alarm` `device`",
"best_access_path": {
"considered_access_paths": [
{
"access_type": "ref",
"index": "index2",
"usable": false,
"chosen": false
},
{
"access_type": "ref",
"index": "xmbh_device_1",
"rows": 2e308,
"cost": 0,
"chosen": false
},
{
"access_type": "ref",
"index": "xmbh_time_1",
"usable": false,
"chosen": false
},
{
"access_type": "range",
"rows": 136677,
"cost": 88081,
"chosen": true
}
]
},
"cost_for_plan": 88081,
"rows_for_plan": 136677,
"rest_of_plan": [
{
"plan_prefix": [
"`t_gj_device_alarm` `device`"
],
"table": "`t_sb_register_info` `info`",
"best_access_path": {
"considered_access_paths": [
{
"access_type": "ref",
"index": "PRIMARY",
"rows": 1,
"cost": 136677,
"chosen": true
},
{
"access_type": "ref",
"index": "index1",
"rows": 1,
"cost": 136677,
"chosen": false
},
{
"access_type": "scan",
"using_join_cache": true,
"rows": 6306,
"cost": 1.72e8,
"chosen": false
}
]
},
"cost_for_plan": 252094,
"rows_for_plan": 136677,
"pruned_by_cost": true
}
]
}
]
},
不工作的原因
"AND device.gjsj >= '2019-03-04'AND device.gjsj <= '2020-03-11'"
{
"refine_plan": [
{
"table": "`t_sb_register_info` `info`",
"access_type": "table_scan"
},
{
"table": "`t_gj_device_alarm` `device`",
"pushed_index_condition": "((`device`.`gjjb` = 'SPSBWXH') or (`device`.`gjjb` = 'SPSBHMBD'))",
"table_condition_attached": "((`device`.`gjsj` >= '2019-03-04') and (`device`.`gjsj` <= '2020-03-11'))"
}
]
}
“ AND device.gjsj在'2019-03-04'和'2020-03-11'之间”
{
"refine_plan": [
{
"table": "`t_sb_register_info` `info`",
"access_type": "table_scan"
},
{
"table": "`t_gj_device_alarm` `device`",
"pushed_index_condition": "((`device`.`gjjb` = 'SPSBWXH') or (`device`.`gjjb` = 'SPSBHMBD'))",
"table_condition_attached": "(`device`.`gjsj` between '2019-03-04' and '2020-03-11')"
}
]
}
我倾向于采用相当“吸取即见”的方法来建立索引，因此我将删除除info.index1和device.index1之外的所有索引，然后重新排列这些索引并查看会发生什么。另外，您可能想将delete_flag添加到信息索引中。
而且，FWIW，我发现这更易于阅读（尽管从性能角度来说，这仅是微不足道的改进）
SELECT device.xmbh
, COALESCE(COUNT(*),0) alarmCount
FROM t_gj_device_alarm device
JOIN t_sb_register_info info
ON info.xmbh = device.xmbh
AND info.device_no = device.device_no
AND info.delete_flag = 0
WHERE device.delete_flag = 0
AND device.gjjb IN('SPSBWXH','SPSBHMBD')
AND device.gjsj >= '2019-03-04'
AND device.gjsj <= '2020-03-11'
GROUP
BY device.xmbh
我建议将查询写为：
select avg( device.gjjb in ('SPSBWXH', 'SPSBHMBD') and
device.gjsj >= '2019-03-04' and
device.gjsj <= '2020-03-11'
) as rate
from t_gj_device_alarm device
where device.delete_flag = 0;
这几乎需要扫描表，除非删除了大多数行。在这种情况下，您可以在delete_flag, gjjb, gjsj)上创建索引。
您不妨考虑从
AND device.gjsj >= '2019-03-04'
AND device.gjsj <= '2020-03-11'
to
AND device.gjsj BETWEEN '2019-03-04' and '2020-03-11'
用于单个范围处理。