1. 聚合函数
1.1 COUNT()
描述:返回单个字段中非空(non-null)值的数量
语法
SELECT COUNT(<field_key>) FROM <measurement_name> [WHERE <stuff>] [GROUP BY <stuff>]
例子:
- 计算字段
water_level
非空值的数量
> SELECT COUNT("water_level") FROM "h2o_feet"
name: h2o_feet
--------------
time count
1970-01-01T00:00:00Z 15258
- 计算字段
water_level
非空值的数量,按时间间隔分组
> SELECT COUNT("water_level") FROM "h2o_feet" WHERE time >= '2015-08-18T00:00:00Z' AND time < '2015-09-18T17:00:00Z' GROUP BY time(4d)
name: h2o_feet
--------------
time count
2015-08-17T00:00:00Z 1440
2015-08-21T00:00:00Z 1920
2015-08-25T00:00:00Z 1920
2015-08-29T00:00:00Z 1920
2015-09-02T00:00:00Z 1915
2015-09-06T00:00:00Z 1920
2015-09-10T00:00:00Z 1920
2015-09-14T00:00:00Z 1920
2015-09-18T00:00:00Z 335
- 表
h2o_feet
有两个数据字段level description
和water_level
,可以通过count(*)
统计所有的字段
> SELECT COUNT(*) FROM "h2o_feet"
name: h2o_feet
--------------
time count_level description count_water_level
1970-01-01T00:00:00Z 15258 15258
1.2 DISTINCT()
说明:返回字段的唯一值(去重)
语法
SELECT DISTINCT(<field_key>) FROM <measurement_name> [WHERE <stuff>] [GROUP BY <stuff>]
例子:
- 全表单字段
> SELECT DISTINCT("level description") FROM "h2o_feet"
name: h2o_feet
--------------
time distinct
1970-01-01T00:00:00Z between 6 and 9 feet
1970-01-01T00:00:00Z below 3 feet
1970-01-01T00:00:00Z between 3 and 6 feet
1970-01-01T00:00:00Z at or greater than 9 feet
- 分组单字段
> SELECT DISTINCT("level description") FROM "h2o_feet" GROUP BY "location"
name: h2o_feet
tags: location=coyote_creek
time distinct
---- --------
1970-01-01T00:00:00Z between 6 and 9 feet
1970-01-01T00:00:00Z between 3 and 6 feet
1970-01-01T00:00:00Z below 3 feet
1970-01-01T00:00:00Z at or greater than 9 feet
name: h2o_feet
tags: location=santa_monica
time distinct
---- --------
1970-01-01T00:00:00Z below 3 feet
1970-01-01T00:00:00Z between 3 and 6 feet
1970-01-01T00:00:00Z between 6 and 9 feet
- 多字段
> SELECT DISTINCT(*) FROM "h2o_feet" LIMIT 5
name: h2o_feet
--------------
time distinct_level description distinct_water_level
1970-01-01T00:00:00Z below 3 feet 2.064
1970-01-01T00:00:00Z between 6 and 9 feet 8.12
1970-01-01T00:00:00Z 2.116
1970-01-01T00:00:00Z 8.005
1970-01-01T00:00:00Z 2.028
1.3 MEAN()
说明:算术平均值,字段类型必须为整型(int64
)或浮点型(float64
)
语法
SELECT MEAN(<field_key>) FROM <measurement_name> [WHERE <stuff>] [GROUP BY <stuff>]
例子:
- 时间在
2016-08-18T00:00:00Z
和2016-09-18T17:00:00Z
之间,按4天(time(4d)
)进行分组
> SELECT MEAN("water_level") FROM "h2o_feet" WHERE time >= '2015-08-18T00:00:00Z' AND time < '2015-09-18T17:00:00Z' GROUP BY time(4d)
name: h2o_feet
--------------
time mean
2016-08-17T00:00:00Z 4.322029861111125
2016-08-21T00:00:00Z 4.251395512375667
2016-08-25T00:00:00Z 4.285036458333324
2016-08-29T00:00:00Z 4.469495801899061
2016-09-02T00:00:00Z 4.382785378590083
2016-09-06T00:00:00Z 4.28849666349042
...
1.4 MEDIAN()
说明:返回中位数,字段类型必须为整型(int64
)或浮点型(float64
),*
表示所有字段
语法
SELECT MEDIAN(<field_key>) FROM <measurement_name> [WHERE <stuff>] [GROUP BY <stuff>]
例子:
> SELECT MEDIAN("water_level") FROM "h2o_feet" WHERE time >= '2015-08-18T00:00:00Z' AND time < '2015-08-18T00:36:00Z' GROUP BY "location"
name: h2o_feet
tags: location = coyote_creek
time median
---- ------
2015-08-18T00:00:00Z 7.8245
name: h2o_feet
tags: location = santa_monica
time median
---- ------
2015-08-18T00:00:00Z 2.0575
1.5 MODE()
说明:返回最频繁的(出现频率最高的)值,如果有多个频率相同的值则返回第一个(最早的)
语法
SELECT MODE(<field_key>) FROM <measurement_name> [WHERE <stuff>] [GROUP BY <stuff>]
例子:
> SELECT MODE("water_level") FROM "h2o_feet" WHERE time >= '2015-08-18T00:00:00Z' AND time < '2015-08-18T00:36:00Z' GROUP BY "location"
name: h2o_feet
tags: location = coyote_creek
time mode
---- ------
2015-08-18T00:00:00Z 7
name: h2o_feet
tags: location = santa_monica
time mode
---- ------
2015-08-18T00:00:00Z 2
1.5 SPREAD()
说明:返回字段的最小值和最大值之间的差值。 该字段必须是int64
或float64
类型; *
表示表中的所有int64
或float64
字段。
语法
SELECT SPREAD(<field_key>) FROM <measurement_name> [WHERE <stuff>] [GROUP BY <stuff>]
例子:
> SELECT SPREAD("water_level") FROM "h2o_feet" WHERE "location" = 'santa_monica' AND time >= '2015-09-18T17:00:00Z' AND time < '2015-09-18T20:30:00Z' GROUP BY time(30m)
name: h2o_feet
--------------
time spread
2015-09-18T17:00:00Z 0.16699999999999982
2015-09-18T17:30:00Z 0.5469999999999997
2015-09-18T18:00:00Z 0.47499999999999964
2015-09-18T18:30:00Z 0.2560000000000002
2015-09-18T19:00:00Z 0.23899999999999988
2015-09-18T19:30:00Z 0.1609999999999996
2015-09-18T20:00:00Z 0.16800000000000015
1.6 SUM()
说明:返回单个字段中所有值的总和。 该字段必须是int64
或float64
类型; *
表示表中的所有int64
或float64
字段。
语法
SELECT SUM(<field_key>) FROM <measurement_name> [WHERE <stuff>] [GROUP BY <stuff>]
例子:
> SELECT SUM("water_level") FROM "h2o_feet" WHERE time >= '2015-08-18T00:00:00Z' AND time < '2015-09-18T17:00:00Z' GROUP BY time(5d)
name: h2o_feet
--------------
time sum
2015-08-18T00:00:00Z 10334.908999999983
2015-08-23T00:00:00Z 10113.356999999995
2015-08-28T00:00:00Z 10663.683000000006
2015-09-02T00:00:00Z 10451.321
2015-09-07T00:00:00Z 10871.817999999994
2015-09-12T00:00:00Z 11459.00099999999
2015-09-17T00:00:00Z 3627.762000000003
1.7 STDDEV()
说明:返回单个字段中的值的标准偏差。 该字段必须是int64
或float64
类型。
语法
SELECT STDDEV(<field_key>) FROM <measurement_name> [WHERE <stuff>] [GROUP BY <stuff>]
2. 选择器函数
2.1 BOTTOM()
说明:返回单个字段中最小的N
个值。 字段类型必须为int64
或float64
。当同步指定tag
时,设定tag
的记录数是X
,如果N
>X
时只返回X
条记录,每个tag
一条,否则返回最小的N
条数据。
语法
SELECT BOTTOM(<field_key>[,<tag_keys>],<N>)[,<tag_keys>] FROM <measurement_name> [WHERE <stuff>] [GROUP BY <stuff>]
2.2 FIRST()
说明:返回单个字段的最旧值(由时间戳确定)。
语法
SELECT FIRST(<field_key>)[,<tag_key(s)>] FROM <measurement_name> [WHERE <stuff>] [GROUP BY <stuff>]
2.3 LAST()
说明:返回单个字段的最新值(由时间戳确定)。
SELECT LAST(<field_key>)[,<tag_key(s)>] FROM <measurement_name> [WHERE <stuff>] [GROUP BY <stuff>]
2.4 MAX()
说明:返回单个字段中的最大值。 该字段必须是int64
,float64
或boolean
。
语法
SELECT MAX(<field_key>)[,<tag_key(s)>] FROM <measurement_name> [WHERE <stuff>] [GROUP BY <stuff>]
2.5 MIN()
说明:返回单个字段中的最小值。 该字段必须是int64
,float64
或boolean
。
语法
SELECT MIN(<field_key>)[,<tag_key(s)>] FROM <measurement_name> [WHERE <stuff>] [GROUP BY <stuff>]
2.6 PERCENTILE()
说明:返回单个字段的排序值的第N
个百分位数值。 该字段必须是int64
或float64
类型。 百分位数N
必须是0
到100
之间的整数或浮点数,包括0
和100
。算法找度娘。
语法
SELECT PERCENTILE(<field_key>, <N>)[,<tag_key(s)>] FROM <measurement_name> [WHERE <stuff>] [GROUP BY <stuff>]
2.7 SAMPLE()
说明:返回指定字段的N
个点的随机抽样。 InfluxDB
使用储层采样来生成随机点。 SAMPLE()
支持所有字段类型。
语法
SELECT SAMPLE(<field_key>,<N>) FROM_clause [WHERE_clause] [GROUP_BY_clause]
2.8 TOP()
说明:返回单个字段中最大的N
个值。 字段类型必须为int64
或float64
。
语法
SELECT TOP(<field_key>[,<tag_keys>],<N>)[,<tag_keys>] FROM <measurement_name> [WHERE <stuff>] [GROUP BY <stuff>]
3. 转换函数
3.1 CUMULATIVE_SUM()
说明:返回单个字段的连续字段值的累积和。 字段类型必须为int64
或float64
。
基础语法
SELECT CUMULATIVE_SUM(<field_key>) FROM_clause WHERE_clause
高级语法
支持如下嵌套函数类型:COUNT()
, MEAN()
, MEDIAN()
, MODE()
, SUM()
, FIRST()
, LAST()
, MIN()
,MAX()
, and PERCENTILE()
.
SELECT CUMULATIVE_SUM(<function>(<field_key>)) FROM_clause WHERE_clause GROUP BY time(<interval>)[,<tag_key>]
例子
##原数据
> 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
##转换后数据
> SELECT CUMULATIVE_SUM("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 cumulative_sum
---- --------------
2015-08-18T00:00:00Z 2.064
2015-08-18T00:06:00Z 4.18
2015-08-18T00:12:00Z 6.208
2015-08-18T00:18:00Z 8.334
2015-08-18T00:24:00Z 10.375
2015-08-18T00:30:00Z 12.426
3.2 DERIVATIVE()
说明:返回系列中单个字段中值的变化率。 InfluxDB计算时间域值之间的差异,并将这些结果转换为单位变化率。 单位参数是可选的,如果未指定,则默认为1秒(1秒)。
基础语法
SELECT DERIVATIVE(<field_key>, [<unit>]) FROM <measurement_name> [WHERE <stuff>]
单位unit
可以有如下值:
-
u
orµ
微妙(microseconds) -
ms
毫秒(milliseconds) -
s
秒(seconds) -
m
分(minutes) -
h
时(hours) -
d
天(days) -
w
周(weeks)
使用聚合函数语法
SELECT DERIVATIVE(AGGREGATION_FUNCTION(<field_key>),[<unit>]) FROM <measurement_name> WHERE <stuff> GROUP BY time(<aggregation_interval>)
例子
#原数据,两条数据直接间隔6分钟
> SELECT "water_level" FROM "h2o_feet" WHERE "location" = 'santa_monica' LIMIT 5
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
#不指定单位时,默认为每秒变化率,如第一条记录(`(2.116-2.064)/(6m/1s)`)
> SELECT DERIVATIVE("water_level") FROM "h2o_feet" WHERE "location" = 'santa_monica' LIMIT 5
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
#每6分钟变化率,如第一条(`(2.116-2.064)/(6m/6m)`)
> SELECT DERIVATIVE("water_level",6m) FROM "h2o_feet" WHERE "location" = 'santa_monica' LIMIT 5
name: h2o_feet
--------------
time derivative
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
#每12分钟变化率,如第一条(`(2.116-2.064)/(6m/12m)`)
> SELECT DERIVATIVE("water_level",12m) FROM "h2o_feet" WHERE "location" = 'santa_monica' LIMIT 5
name: h2o_feet
--------------
time derivative
2015-08-18T00:06:00Z 0.10400000000000009
2015-08-18T00:12:00Z -0.17600000000000016
2015-08-18T00:18:00Z 0.19599999999999973
2015-08-18T00:24:00Z -0.16999999999999993
2015-08-18T00:30:00Z 0.020000000000000462
#每隔12分钟最大值
> SELECT MAX("water_level") FROM "h2o_feet" WHERE "location" = 'santa_monica' AND time >= '2015-08-18T00:00:00Z' AND time < '2015-08-18T00:36:00Z' GROUP BY time(12m)
name: h2o_feet
--------------
time max
2015-08-18T00:00:00Z 2.116
2015-08-18T00:12:00Z 2.126
2015-08-18T00:24:00Z 2.051
#每隔12分钟变化率,如第一条(`(2.126-2.116)/(12m-12m)`),带group by 语句时unit默认为time函数指定的间隔
> SELECT DERIVATIVE(MAX("water_level")) FROM "h2o_feet" WHERE "location" = 'santa_monica' AND time >= '2015-08-18T00:00:00Z' AND time < '2015-08-18T00:36:00Z' GROUP BY time(12m)
name: h2o_feet
--------------
time derivative
2015-08-18T00:12:00Z 0.009999999999999787
2015-08-18T00:24:00Z -0.07499999999999973
#每隔18分钟汇总数据
> SELECT SUM("water_level") FROM "h2o_feet" WHERE "location" = 'santa_monica' AND time >= '2015-08-18T00:00:00Z' AND time < '2015-08-18T00:36:00Z' GROUP BY time(18m)
name: h2o_feet
--------------
time sum
2015-08-18T00:00:00Z 6.208
2015-08-18T00:18:00Z 6.218
#每隔18分钟汇总数据没6分钟变化率,如第一条(`(6.218-6.208)/(18m/6m)`)
> SELECT DERIVATIVE(SUM("water_level"),6m) FROM "h2o_feet" WHERE "location" = 'santa_monica' AND time >= '2015-08-18T00:00:00Z' AND time < '2015-08-18T00:36:00Z' GROUP BY time(18m)
name: h2o_feet
--------------
time derivative
2015-08-18T00:18:00Z 0.0033333333333332624
3.3 DIFFERENCE()
说明:返回单个字段中连续的时间顺序值之间的差异。 字段类型必须为int64
或float64
。
基础语法
SELECT DIFFERENCE(<field_key>) FROM <measurement_name> [WHERE <stuff>]
高级语法
SELECT DIFFERENCE(<function>(<field_key>)) FROM <measurement_name> WHERE <stuff> GROUP BY time(<time_interval>)
支持的内嵌函数包括:COUNT()
, MEAN()
, MEDIAN()
, SUM()
, FIRST()
,LAST()
, MIN()
, MAX()
, and PERCENTILE()
。
例子
#带处理数据
> SELECT "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 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
2015-08-18T00:36:00Z 2.067
#处理后
> 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
#分组统计后数据
> SELECT MIN("water_level") FROM "h2o_feet" WHERE "location"='santa_monica' AND time >= '2015-08-18T00:00:00Z' AND time <= '2015-08-18T00:36:00Z' GROUP BY time(12m)
name: h2o_feet
--------------
time min
2015-08-18T00:00:00Z 2.064
2015-08-18T00:12:00Z 2.028
2015-08-18T00:24:00Z 2.041
2015-08-18T00:36:00Z 2.067
#分组统计处理后数据
> SELECT DIFFERENCE(MIN("water_level")) FROM "h2o_feet" WHERE "location"='santa_monica' AND time >= '2015-08-18T00:00:00Z' AND time <= '2015-08-18T00:36:00Z' GROUP BY time(12m)
name: h2o_feet
--------------
time difference
2015-08-18T00:12:00Z -0.03600000000000003
2015-08-18T00:24:00Z 0.0129999999999999
2015-08-18T00:36:00Z 0.026000000000000245
3.4 ELAPSED()
说明:返回单个字段中后续时间戳之间的差异。 持续时间(unit
)参数是可选的,如果未指定,则默认为一纳秒。
语法
SELECT ELAPSED(<field_key>, <unit>) FROM <measurement_name> [WHERE <stuff>]
例子
#原数据
> SELECT "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 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
#每两个`water_level`数据记录直接的时间间隔是6分钟(即360000000000纳秒),elapsed = 6m/1纳秒
> SELECT ELAPSED("water_level") FROM "h2o_feet" WHERE "location" = 'santa_monica' AND time >= '2015-08-18T00:00:00Z' AND time <= '2015-08-18T00:24:00Z'
name: h2o_feet
--------------
time elapsed
2015-08-18T00:06:00Z 360000000000
2015-08-18T00:12:00Z 360000000000
2015-08-18T00:18:00Z 360000000000
2015-08-18T00:24:00Z 360000000000
#每两个`water_level`数据记录直接的时间间隔是6分钟,elapsed = 6m/1m
> SELECT ELAPSED("water_level",1m) FROM "h2o_feet" WHERE "location" = 'santa_monica' AND time >= '2015-08-18T00:00:00Z' AND time <= '2015-08-18T00:24:00Z'
name: h2o_feet
--------------
time elapsed
2015-08-18T00:06:00Z 6
2015-08-18T00:12:00Z 6
2015-08-18T00:18:00Z 6
2015-08-18T00:24:00Z 6
#每两个`water_level`数据记录直接的时间间隔是6分钟,elapsed = 6m / 1h。因为1h>6m,所以数据为0
> SELECT ELAPSED("water_level",1h) FROM "h2o_feet" WHERE "location" = 'santa_monica' AND time >= '2015-08-18T00:00:00Z' AND time <= '2015-08-18T00:24:00Z'
name: h2o_feet
--------------
time elapsed
2015-08-18T00:06:00Z 0
2015-08-18T00:12:00Z 0
2015-08-18T00:18:00Z 0
2015-08-18T00:24:00Z 0
3.5 MOVING_AVERAGE()
说明:返回单个字段的连续window
个字段值的滑动平均值。 字段类型必须为int64
或float64
。算法找度娘
基础语法
SELECT MOVING_AVERAGE(<field_key>,<window>) FROM <measurement_name> [WHERE <stuff>]
高级语法
SELECT MOVING_AVERAGE(<function>(<field_key>),<window>) FROM <measurement_name> WHERE <stuff> GROUP BY time(<time_interval>)
支持的函数包括:COUNT()
, MEAN()
, MEDIAN()
, SUM()
, FIRST()
,LAST()
, MIN()
, MAX()
, and PERCENTILE()
。
例子
> SELECT "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 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
2015-08-18T00:36:00Z 2.067
#第一条(`(2.116+2.064)/2`),第二条(`(2.028+2.116)/2`)
> SELECT MOVING_AVERAGE("water_level",2) 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 moving_average
2015-08-18T00:06:00Z 2.09
2015-08-18T00:12:00Z 2.072
2015-08-18T00:18:00Z 2.077
2015-08-18T00:24:00Z 2.0835
2015-08-18T00:30:00Z 2.0460000000000003
2015-08-18T00:36:00Z 2.059
#分组统计
> SELECT MIN("water_level") FROM "h2o_feet" WHERE "location" = 'santa_monica' AND time >= '2015-08-18T00:00:00Z' AND time <= '2015-08-18T00:36:00Z' GROUP BY time(12m)
name: h2o_feet
--------------
time min
2015-08-18T00:00:00Z 2.064
2015-08-18T00:12:00Z 2.028
2015-08-18T00:24:00Z 2.041
2015-08-18T00:36:00Z 2.067
#分组统计滑动平均值,第一条(`(2.064+2.028)/2`)
> SELECT MOVING_AVERAGE(MIN("water_level"),2) FROM "h2o_feet" WHERE "location" = 'santa_monica' AND time >= '2015-08-18T00:00:00Z' AND time <= '2015-08-18T00:36:00Z' GROUP BY time(12m)
name: h2o_feet
--------------
time moving_average
2015-08-18T00:12:00Z 2.0460000000000003
2015-08-18T00:24:00Z 2.0345000000000004
2015-08-18T00:36:00Z 2.0540000000000003
3.6 NON_NEGATIVE_DERIVATIVE()
说明:返回系列中单个字段中的值的非负变化率。 InfluxDB计算时间域值之间的差异,并将这些结果转换为单位变化率。 单位参数是可选的,如果未指定,则默认为1秒(1秒)。改函数和DERIVATIVE()函数类似,只是返回其正数结果。
语法
SELECT NON_NEGATIVE_DERIVATIVE(<field_key>, [<unit>]) FROM <measurement_name> [WHERE <stuff>]
SELECT NON_NEGATIVE_DERIVATIVE(AGGREGATION_FUNCTION(<field_key>),[<unit>]) FROM <measurement_name> WHERE <stuff> GROUP BY time(<aggregation_interval>)
4. 预测函数
4.1 HOLT_WINTERS()
说明:霍尔特指数平滑法,该字段必须是int64
或float64
类型。算法找度娘。
语法
SELECT HOLT_WINTERS(FUNCTION(<field_key>),<N>,<S>) FROM <measurement_name> WHERE <stuff> GROUP BY time(<interval>)[,<stuff>]
SELECT HOLT_WINTERS_WITH_FIT(FUNCTION(<field_key>),<N>,<S>) FROM <measurement_name> WHERE <stuff> GROUP BY time(<interval>)[,<stuff>]