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Constant Timeseries Generating Functions

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Constant Timeseries Generating Functions

The constant timeseries generating function is used to generate a timeseries in which the values of all data points are the same.

The constant timeseries generating function accepts one or more timeseries inputs, and the timestamp set of the output data points is the union of the timestamp sets of the input timeseries.

Currently, IoTDB supports the following constant timeseries generating functions:

Function NameRequired AttributesOutput Series Data TypeDescription
CONSTvalue: the value of the output data point
type: the type of the output data point, it can only be INT32 / INT64 / FLOAT / DOUBLE / BOOLEAN / TEXT
Determined by the required attribute typeOutput the user-specified constant timeseries according to the attributes value and type.
PINoneDOUBLEData point value: a double value of π, the ratio of the circumference of a circle to its diameter, which is equals to Math.PI in the Java Standard Library.
ENoneDOUBLEData point value: a double value of e, the base of the natural logarithms, which is equals to Math.E in the Java Standard Library.

Example:

select s1, s2, const(s1, 'value'='1024', 'type'='INT64'), pi(s2), e(s1, s2) from root.sg1.d1; 

Result:

select s1, s2, const(s1, 'value'='1024', 'type'='INT64'), pi(s2), e(s1, s2) from root.sg1.d1; 
+-----------------------------+--------------+--------------+-----------------------------------------------------+------------------+---------------------------------+
|                         Time|root.sg1.d1.s1|root.sg1.d1.s2|const(root.sg1.d1.s1, "value"="1024", "type"="INT64")|pi(root.sg1.d1.s2)|e(root.sg1.d1.s1, root.sg1.d1.s2)|
+-----------------------------+--------------+--------------+-----------------------------------------------------+------------------+---------------------------------+
|1970-01-01T08:00:00.000+08:00|           0.0|           0.0|                                                 1024| 3.141592653589793|                2.718281828459045|
|1970-01-01T08:00:00.001+08:00|           1.0|          null|                                                 1024|              null|                2.718281828459045|
|1970-01-01T08:00:00.002+08:00|           2.0|          null|                                                 1024|              null|                2.718281828459045|
|1970-01-01T08:00:00.003+08:00|          null|           3.0|                                                 null| 3.141592653589793|                2.718281828459045|
|1970-01-01T08:00:00.004+08:00|          null|           4.0|                                                 null| 3.141592653589793|                2.718281828459045|
+-----------------------------+--------------+--------------+-----------------------------------------------------+------------------+---------------------------------+
Total line number = 5
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