public final class InternalRowMergerFunction extends ScalarFunction
The function uses a custom TypeInference and thus disables any of the default
reflection-based logic. It returns internal data structures for both input and output types of
the eval method.
For code readability, we might use some internal utility methods that should rarely change. Implementers can copy those if they don't want to rely on non-official API.
| Constructor and Description |
|---|
InternalRowMergerFunction() |
| Modifier and Type | Method and Description |
|---|---|
RowData |
eval(RowData r1,
RowData r2) |
TypeInference |
getTypeInference(DataTypeFactory typeFactory)
Returns the logic for performing type inference of a call to this function definition.
|
getKind, getParameterTypes, getResultTypeclose, functionIdentifier, open, toStringclone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, waitgetRequirements, isDeterministicpublic TypeInference getTypeInference(DataTypeFactory typeFactory)
UserDefinedFunctionThe type inference process is responsible for inferring unknown types of input arguments, validating input arguments, and producing result types. The type inference process happens independent of a function body. The output of the type inference is used to search for a corresponding runtime implementation.
Instances of type inference can be created by using TypeInference.newBuilder().
See BuiltInFunctionDefinitions for concrete usage examples.
The type inference for user-defined functions is automatically extracted using reflection.
It does this by analyzing implementation methods such as eval() or accumulate() and
the generic parameters of a function class if present. If the reflective information is not
sufficient, it can be supported and enriched with DataTypeHint and FunctionHint annotations.
Note: Overriding this method is only recommended for advanced users. If a custom type inference is specified, it is the responsibility of the implementer to make sure that the output of the type inference process matches with the implementation method:
The implementation method must comply with each DataType.getConversionClass()
returned by the type inference. For example, if DataTypes.TIMESTAMP(3).bridgedTo(java.sql.Timestamp.class) is an expected argument type, the
method must accept a call eval(java.sql.Timestamp).
Regular Java calling semantics (including type widening and autoboxing) are applied when
calling an implementation method which means that the signature can be eval(java.lang.Object).
The runtime will take care of converting the data to the data format specified by the
DataType.getConversionClass() coming from the type inference logic.
getTypeInference in interface FunctionDefinitiongetTypeInference in class ScalarFunctionCopyright © 2014–2024 The Apache Software Foundation. All rights reserved.