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Beyyes merged 2 commits into from
Aug 25, 2023
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Add count_time aggregation usage doc #73

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add count time usage
Beyyes Aug 24, 2023
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fix
Beyyes Aug 24, 2023
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143 changes: 127 additions & 16 deletions src/UserGuide/Master/stage/Operators-Functions/Aggregation.md
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Original file line number Diff line number Diff line change
Expand Up @@ -27,21 +27,23 @@ All aggregate functions except `COUNT()`, `COUNT_IF()` ignore null values and re

The aggregate functions supported by IoTDB are as follows:

| Function Name | Description | Allowed Input Series Data Types | Required Attributes | Output Series Data Type |
| ------------- | ------------------------------------------------------------ | ------------------------------- | ------------------------------------------------------------ | ----------------------------------- |
| SUM | Summation. | INT32 INT64 FLOAT DOUBLE | / | DOUBLE |
| COUNT | Counts the number of data points. | All data types | / | INT |
| AVG | Average. | INT32 INT64 FLOAT DOUBLE | / | DOUBLE |
| EXTREME | Finds the value with the largest absolute value. Returns a positive value if the maximum absolute value of positive and negative values is equal. | INT32 INT64 FLOAT DOUBLE | / | Consistent with the input data type |
| MAX_VALUE | Find the maximum value. | INT32 INT64 FLOAT DOUBLE | / | Consistent with the input data type |
| MIN_VALUE | Find the minimum value. | INT32 INT64 FLOAT DOUBLE | / | Consistent with the input data type |
| FIRST_VALUE | Find the value with the smallest timestamp. | All data types | / | Consistent with input data type |
| LAST_VALUE | Find the value with the largest timestamp. | All data types | / | Consistent with input data type |
| MAX_TIME | Find the maximum timestamp. | All data Types | / | Timestamp |
| MIN_TIME | Find the minimum timestamp. | All data Types | / | Timestamp |
| COUNT_IF | Find the number of data points that continuously meet a given condition and the number of data points that meet the condition (represented by keep) meet the specified threshold. | BOOLEAN | `[keep >=/>/=/!=/</<=]threshold`：The specified threshold or threshold condition, it is equivalent to `keep >= threshold` if `threshold` is used alone, type of `threshold` is `INT64` `ignoreNull`：Optional, default value is `true`；If the value is `true`, null values are ignored, it means that if there is a null value in the middle, the value is ignored without interrupting the continuity. If the value is `true`, null values are not ignored, it means that if there are null values in the middle, continuity will be broken | INT64 |
| TIME_DURATION | Find the difference between the timestamp of the largest non-null value and the timestamp of the smallest non-null value in a column | All data Types | / | INT64 |
| MODE | Find the mode. Note: 1.Having too many different values in the input series risks a memory exception; 2.If all the elements have the same number of occurrences, that is no Mode, return the value with earliest time; 3.If there are many Modes, return the Mode with earliest time. | All data Types | / | Consistent with the input data type |
| Function Name | Description | Allowed Input Series Data Types | Required Attributes | Output Series Data Type |
| ------------- | ------------------------------------------------------------ |-----------------------------------------------------| ------------------------------------------------------------ | ----------------------------------- |
| SUM | Summation. | INT32 INT64 FLOAT DOUBLE | / | DOUBLE |
| COUNT | Counts the number of data points. | All data types | / | INT |
| AVG | Average. | INT32 INT64 FLOAT DOUBLE | / | DOUBLE |
| EXTREME | Finds the value with the largest absolute value. Returns a positive value if the maximum absolute value of positive and negative values is equal. | INT32 INT64 FLOAT DOUBLE | / | Consistent with the input data type |
| MAX_VALUE | Find the maximum value. | INT32 INT64 FLOAT DOUBLE | / | Consistent with the input data type |
| MIN_VALUE | Find the minimum value. | INT32 INT64 FLOAT DOUBLE | / | Consistent with the input data type |
| FIRST_VALUE | Find the value with the smallest timestamp. | All data types | / | Consistent with input data type |
| LAST_VALUE | Find the value with the largest timestamp. | All data types | / | Consistent with input data type |
| MAX_TIME | Find the maximum timestamp. | All data Types | / | Timestamp |
| MIN_TIME | Find the minimum timestamp. | All data Types | / | Timestamp |
| COUNT_IF | Find the number of data points that continuously meet a given condition and the number of data points that meet the condition (represented by keep) meet the specified threshold. | BOOLEAN | `[keep >=/>/=/!=/</<=]threshold`：The specified threshold or threshold condition, it is equivalent to `keep >= threshold` if `threshold` is used alone, type of `threshold` is `INT64` `ignoreNull`：Optional, default value is `true`；If the value is `true`, null values are ignored, it means that if there is a null value in the middle, the value is ignored without interrupting the continuity. If the value is `true`, null values are not ignored, it means that if there are null values in the middle, continuity will be broken | INT64 |
| TIME_DURATION | Find the difference between the timestamp of the largest non-null value and the timestamp of the smallest non-null value in a column | All data Types | / | INT64 |
| MODE | Find the mode. Note: 1.Having too many different values in the input series risks a memory exception; 2.If all the elements have the same number of occurrences, that is no Mode, return the value with earliest time; 3.If there are many Modes, return the Mode with earliest time. | All data Types | / | Consistent with the input data type |
| COUNT_TIME | The number of timestamps in the query data set. When used with `align by device`, the result is the number of timestamps in the data set per device. | All data Types, the input parameter can only be `*` | / | INT64 |


## COUNT

Expand Down Expand Up @@ -179,4 +181,113 @@ Result:
| 1677570933|
+----------------------------+
```
> Note: Returns 0 if there is only one data point, or null if the data point is null.
> Note: Returns 0 if there is only one data point, or null if the data point is null.

## COUNT_TIME
### Grammar
```sql
count_time(*)
```
### Example
#### raw data
```
+----------+-------------+-------------+-------------+-------------+
| Time|root.db.d1.s1|root.db.d1.s2|root.db.d2.s1|root.db.d2.s2|
+----------+-------------+-------------+-------------+-------------+
| 0| 0| null| null| 0|
| 1| null| 1| 1| null|
| 2| null| 2| 2| null|
| 4| 4| null| null| 4|
| 5| 5| 5| 5| 5|
| 7| null| 7| 7| null|
| 8| 8| 8| 8| 8|
| 9| null| 9| null| null|
+----------+-------------+-------------+-------------+-------------+
```
#### Insert sql
```sql
CREATE DATABASE root.db;
CREATE TIMESERIES root.db.d1.s1 WITH DATATYPE=INT32, ENCODING=PLAIN;
CREATE TIMESERIES root.db.d1.s2 WITH DATATYPE=INT32, ENCODING=PLAIN;
CREATE TIMESERIES root.db.d2.s1 WITH DATATYPE=INT32, ENCODING=PLAIN;
CREATE TIMESERIES root.db.d2.s2 WITH DATATYPE=INT32, ENCODING=PLAIN;
INSERT INTO root.db.d1(time, s1) VALUES(0, 0), (4,4), (5,5), (8,8);
INSERT INTO root.db.d1(time, s2) VALUES(1, 1), (2,2), (5,5), (7,7), (8,8), (9,9);
INSERT INTO root.db.d2(time, s1) VALUES(1, 1), (2,2), (5,5), (7,7), (8,8);
INSERT INTO root.db.d2(time, s2) VALUES(0, 0), (4,4), (5,5), (8,8);
```

Query-Example - 1:
```sql
select count_time(*) from root.db.**
```

Result
```
+-------------+
|count_time(*)|
+-------------+
| 8|
+-------------+
```

Query-Example - 2:
```sql
select count_time(*) from root.db.d1, root.db.d2
```

Result
```
+-------------+
|count_time(*)|
+-------------+
| 8|
+-------------+
```

Query-Example - 3:
```sql
select count_time(*) from root.db.** group by([0, 10), 2ms)
```

Result
```
+-----------------------------+-------------+
| Time|count_time(*)|
+-----------------------------+-------------+
|1970-01-01T08:00:00.000+08:00| 2|
|1970-01-01T08:00:00.002+08:00| 1|
|1970-01-01T08:00:00.004+08:00| 2|
|1970-01-01T08:00:00.006+08:00| 1|
|1970-01-01T08:00:00.008+08:00| 2|
+-----------------------------+-------------+
```

Query-Example - 4:
```sql
select count_time(*) from root.db.** group by([0, 10), 2ms) align by device
```

Result
```
+-----------------------------+----------+-------------+
| Time| Device|count_time(*)|
+-----------------------------+----------+-------------+
|1970-01-01T08:00:00.000+08:00|root.db.d1| 2|
|1970-01-01T08:00:00.002+08:00|root.db.d1| 1|
|1970-01-01T08:00:00.004+08:00|root.db.d1| 2|
|1970-01-01T08:00:00.006+08:00|root.db.d1| 1|
|1970-01-01T08:00:00.008+08:00|root.db.d1| 2|
|1970-01-01T08:00:00.000+08:00|root.db.d2| 2|
|1970-01-01T08:00:00.002+08:00|root.db.d2| 1|
|1970-01-01T08:00:00.004+08:00|root.db.d2| 2|
|1970-01-01T08:00:00.006+08:00|root.db.d2| 1|
|1970-01-01T08:00:00.008+08:00|root.db.d2| 1|
+-----------------------------+----------+-------------+
```

> Note:
> 1. The parameter in count_time can only be *.
> 2. Count_time aggregation cannot be used with other aggregation functions.
> 3. Count_time aggregation used with having statement is not supported, and count_time aggregation can not appear in the having statement.
> 4. Count_time does not support use with group by level, group by tag.
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