Structure of DSP function descriptions

The following list provides an overview of how the information about each DSP function is presented in this manual.

Some sections are applicable only to specific categories of functions. See DSP functions by category for more information about each category.

Description

Describes what the function does. This section includes details about how to use the function. For more complex functions, further details and examples might be provided in a separate Usage section.

Function input

Describes the data that the function accepts as input. For example, some functions accept only string values, and others accept timestamp values in a specific syntax. In some cases, the function input is collection<record<R>>, which means that data enters the function as a collection of records with schema <R>. A collection is a list of records.

Function output

Describes the data type or syntax of the data that the function emits as output. In some cases, the function output is collection<record<S>>, which means that data exits the function as a collection of records with schema <S>. A collection is a list of records.

Syntax

Describes the accepted syntax for specifying all the arguments for the function. Applicable only to streaming functions. Required arguments are shown in bold and enclosed in angle brackets ( < > ). Optional arguments are enclosed in square brackets ( [ ] ). Some functions have arguments that accept only a specific set of options. These sets of options are listed in the appropriate argument description under Required arguments or Optional arguments.

Required arguments

Describes the required arguments, including the supported syntax and examples for each argument.

Optional arguments

Describes the optional arguments, including the supported syntax and examples for each argument. Default values, if applicable, are also listed.

Usage

Contains additional information about how to use the function.

SPL2 example

Contains examples of how to use the function. Because scalar functions operate in the context of streaming functions, the scalar function examples might include a streaming function that it's operating within. For instance, an example for the cast scalar function might be | eval body=cast(body, "string"). This example shows the cast scalar function being used within an eval streaming function.