pengzhiwei created CALCITE-3000:
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Summary: Improve SqlUserDefinedFunction and
SqlUserDefinedTableFunction to support override method call
Key: CALCITE-3000
URL: https://issues.apache.org/jira/browse/CALCITE-3000
Project: Calcite
Issue Type: Improvement
Components: core
Reporter: pengzhiwei
Assignee: pengzhiwei
Currently the ModelHandler adds one Function to the schema for one java
method. For the scalar function,ModelHandler resolves all the method in the
class and translate each of them to ScalarFunction to support override method
call. But for TableFunction, this has not been support yet.
Maybe we can support it as the scalar function does. However in that way,
one sql function may match multiple Functions in the schema.I think this is not
a good way. It is better to have only one Function in the schema for one sql
function just like the BuildIn operator.
I'd like to support a new operand type check strategy for
SqlUserDefinedFunction and SqlUserDefinedTableFunction which can infer the
operand type and return type according to the input parameter types.
I will extend the Types#lookupMethod to support finding the best method in
all of the override methods in a class. And the
SqlReturnTypeInference、SqlOperandTypeInference and
SqlOperandTypeChecker can use this to do the type inference according to the
input types. I think it is a dynamically way compared with the original way.
Any suggestion is welcomed,thanks!
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