THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
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Table of Contents
Motivation
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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 truefalse;
/**
* 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 {}; } |
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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