influxdb 常用操作

数据

> SELECT "water_level" FROM "h2o_feet" WHERE time >= '2015-08-18T00:00:00Z' AND time <= '2015-08-18T00:30:00Z' AND "location" = 'santa_monica'

name: h2o_feet
time                   water_level
----                   -----------
2015-08-18T00:00:00Z   2.064
2015-08-18T00:06:00Z   2.116
2015-08-18T00:12:00Z   2.028
2015-08-18T00:18:00Z   2.126
2015-08-18T00:24:00Z   2.041
2015-08-18T00:30:00Z   2.051

 

fill

填充默认值

例子

select sum(*) from water_level where time > new() -5m group by time(1m) fill(3)

解释：

意思是group by time 的时间维度如果没有数据的话用 3填充

DERIVATIVE

返回相邻两组数据的变化率

语法：

SELECT DERIVATIVE(<field_key>, [<unit>]) FROM <measurement_name> [WHERE <stuff>]

其中，unit取值可以为以下几种：

u --microseconds
s --seconds
m --minutes
h --hours
d --days
w --weeks

 

例子

> SELECT DERIVATIVE("water_level",3m) FROM "h2o_feet" WHERE "location" = 'santa_monica' AND time >= '2015-08-18T00:00:00Z' AND time <= '2015-08-18T00:30:00Z'

name: h2o_feet
time                   derivative
----                   ----------
2015-08-18T00:06:00Z   0.00014444444444444457
2015-08-18T00:12:00Z   -0.00024444444444444465
2015-08-18T00:18:00Z   0.0002722222222222218
2015-08-18T00:24:00Z   -0.000236111111111111
2015-08-18T00:30:00Z   2.777777777777842e-05

解释：

计算结果的原理：(2.116 - 2.064) / (6m / 3m)

变化率说明：(06分的值-00分的值)  / (06分 到00分的间隔时间 / 3m)

DIFFERENCE

返回响铃两组数据的差值

> SELECT DIFFERENCE(water_level) FROM h2o_feet WHERE location='santa_monica' AND time >= '2015-08-18T00:00:00Z' and time <= '2015-08-18T00:36:00Z'
name: h2o_feet
--------------
time                            difference
2015-08-18T00:06:00Z      0.052000000000000046
2015-08-18T00:12:00Z      -0.08800000000000008
2015-08-18T00:18:00Z      0.09799999999999986
2015-08-18T00:24:00Z      -0.08499999999999996
2015-08-18T00:30:00Z      0.010000000000000231
2015-08-18T00:36:00Z      0.016000000000000014

解释：这个很好理解了，就是差值