THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
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Table of Contents
Motivation
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Introduce a new annotation to specify the parameter name, indicate if it is optional, and potentially support specifying default values in the future.
Deprecate the ArgumentNames annotation argumentNames method in FunctionHints as it is not user-friendly for specifying argument names with optional configuration.
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public @interface ArgumentHint {
/**
* The name of the parameter, default is an empty string.
*/
String name() default "";
/**
* Whether the parameter is optional, default is truefalse.
*/
boolean isOptional() default true() default false;
/**
* The data type hint for the parameter.
*/
DataTypeHint type() default @DataTypeHint();
} |
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public @interface FunctionHint {
/**
* Deprecated attribute for specifying the names of the arguments.
* It is no longer recommended to use this attribute.
*/
@Deprecated
String[] argumentNames() default {""};
/**
* Attribute for specifying the hints and additional information for function arguments.
*/
ArgumentHint[] arguments() default {};
} |
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public @interface ProcedureHint {
/**
* Deprecated attribute for specifying the names of the arguments.
* It is no longer recommended to use this attribute.
*/
@Deprecated
String[] argumentNames() default {""};
/**
* Attribute for specifying the hints and additional information for procedure arguments.
*/
ArgumentHint[] arguments() default {};
} |
Develop functions or call procedures that support named parameters
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// UDF Development
public static class NamedArgumentsTableFunction extends TableFunction<Object> {
// Example usage: SELECT * FROM TABLE(my_table_function(in1 => 'value1', in2 => 'value2'))
// Example usage: SELECT * FROM TABLE(my_table_function(in1 => 'value1', in2 => 'value2', in3 => 'value3'))
@FunctionHint(
input = {@DataTypeHint("STRING"), @DataTypeHint(value = "STRING"), @DataTypeHint(value = "STRING")},
output = @DataTypeHint("STRING"),
arguments = {
@ArgumentHint(name = "in1", isOptional = true, type = @DataTypeHint("STRING")),
@ArgumentHint(name = "in2", isOptional = true, type = @DataTypeHint("STRING"))
@ArgumentHint(name = "in3", isOptional = true, type = @DataTypeHint("STRING"))})
public void eval(String arg1, String arg2, String arg3) {
collect(arg1 + ", " + arg2 + "," + arg3);
}
}
// Call Procedure Development
public static class NamedArgumentsProcedure implements Procedure {
// Example usage: CALL myNamedProcedure(in1 => 'value1', in2 => 'value2')
// Example usage: CALL myNamedProcedure(in1 => 'value1', in2 => 'value2', in3 => 'value3')
@ProcedureHint(
input = {@DataTypeHint(value = "STRING"), @DataTypeHint(value = "STRING"), @DataTypeHint(value = "STRING")},
output = @DataTypeHint("STRING"),
arguments = {
@ArgumentHint(name = "in1", isOptional = false, type = @DataTypeHint("STRING")),
@ArgumentHint(name = "in2", isOptional = true, type = @DataTypeHint("STRING"))
@ArgumentHint(name = "in3", isOptional = true, type = @DataTypeHint("STRING"))})
public String[] call(ProcedureContext procedureContext, String arg1, String arg2, String arg3) {
return new String[]{arg1 + ", " + arg2 + "," + arg3};
}
} |
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To validate this feature, we can develop custom UDFs or call procedures and use named parameters when invoking them.
Rejected Alternatives
None
1 . https://issues.apache.org/jira/browse/CALCITE-947
2. poc: https://github.com/apache/flink/compare/master...hackergin:flink:poc_named_argument