Aggregate functions are used to perform operations such as sum on aggregated set of events through a window. Usage of an aggregate function is as follows.
@info(name = 'query1')
from cseEventStream#window.timeBatch(1 sec)
select symbol, sum(price) as price
insert into resultStream;
Following are the supported inbuilt aggregate functions of Siddhi.
Sum
| Syntax | <long|double> sum(<int|long|double|float> arg) |
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| Extension Type | Aggregate Function |
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| Description | Calculates the sum for all the events. |
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| Parameter | The value that needs to be summed. |
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| Return Type | Returns long if the input parameter type is int or long, and returns double if the input parameter type is float or double. |
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| Examples | sum(20) returns the sum of 20s as a long value for each event arrival and expiry. sum(temp) returns the sum of all temp attributes based on each event arrival and expiry.
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Average
| Syntax | <double> avg(<int|long|double|float> arg) |
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| Extension Type | Aggregate Function |
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| Description | Calculates the average for all the events. |
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| Parameter | arg: The value that need to be averaged. |
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| Return Type | Returns the calculated average value as a double. |
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| Example | avg(temp) returns the average temp value for all the events based on their arrival and expiry. |
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Maximum
| Syntax | <int|long|double|float> max(<int|long|double|float> arg) |
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| Extension Type | Aggregate Function |
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| Description | Returns the maximum value for all the events. |
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| Parameter | arg: The value that needs to be compared to find the maximum value. |
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| Return Type | Returns the maximum value in the same data type as the input. |
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| Example | max(temp) returns the maximum temp value recorded for all the events based on their arrival and expiry. |
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Minimum
| Syntax | <int|long|double|float> min(<int|long|double|float> arg) |
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| Extension Type | Aggregate Function |
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| Description | Returns the minimum value for all the events. |
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| Parameter | arg: The value that needs to be compared to find the minimum value. |
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| Return Type | Returns the minimum value in the same type as the input. |
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| Example | min(temp) returns the minimum temp value recorded for all the events based on their arrival and expiry. |
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Count
| Syntax | <long> count() |
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| Extension Type | Aggregate Function |
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| Description | Returns the count of all the events. |
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| Return Type | Returns the event count as a long. |
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| Example | count() returns the count of all the events. |
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Standard Deviation
| Syntax | <double> stddev(<int|long|double|float> arg) |
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| Extension Type | Aggregate Function |
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| Description | Returns the calculated standard deviation for all the events. |
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| Parameter | arg: The value that should be used to calculate the standard deviation. |
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| Return Type | Returns the calculated standard deviation value as a double. |
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| Example | stddev(temp) returns the calculated standard deviation of temp for all the events based on their arrival and expiry. |
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Distinct Count
| Syntax | <long> distinctcount(<int|long|double|float|string> arg) |
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| Extension Type | Aggregate Function |
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| Description | Returns the count of distinct occurrences for a given arg. |
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| Parameter | arg: The value that should be counted. |
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| Return Type | Returns the count of distinct occurances for a given arg. |
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| Example | distinctcount(pageID) for the following output returns 3.
"WEB_PAGE_1"
"WEB_PAGE_1"
"WEB_PAGE_2"
"WEB_PAGE_3"
"WEB_PAGE_1"
"WEB_PAGE_2"
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Forever Maximum
| Syntax | <int|long|double|float> maxForever (<int|long|double|float> arg) |
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| Extension Type | Aggregate Function |
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| Description | This is the attribute aggregator to store the maximum value for a given attribute throughout the lifetime of the query regardless of any windows in-front. |
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| Parameter | arg: The value that needs to be compared to find the maximum value. |
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| Return Type | Returns the maximum value in the same data type as the input. |
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| Example | maxForever(temp) returns the maximum temp value recorded for all the events throughout the lifetime of the query. |
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Forever Minimum
| Syntax | <int|long|double|float> minForever (<int|long|double|float> arg) |
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| Extension Type | Aggregate Function |
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| Description | This is the attribute aggregator to store the minimum value for a given attribute throughout the lifetime of the query regardless of any windows in-front. |
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| Parameter | arg: The value that needs to be compared to find the minimum value. |
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| Return Type | Returns the minimum value in the same data type as the input. |
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| Example | minForever(temp) returns the minimum temp value recorded for all the events throughout the lifetime of the query. |
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