Sean Hsuan-Yi Chu created CALCITE-1170:
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Summary: Set Operator is not overridden as the usual SqlOperator
Key: CALCITE-1170
URL: https://issues.apache.org/jira/browse/CALCITE-1170
Project: Calcite
Issue Type: Improvement
Components: core
Reporter: Sean Hsuan-Yi Chu
Assignee: Sean Hsuan-Yi Chu
Calcite allows operators in SqlStdOperatorTable to be overridden when users
would like to have their customized operators to be used instead. (see
[CALCITE-1062] as an example).
If this logic is applied to SqlSetOperator, the systems which leverage Calcite
can define their own output types (based on customized implicit casting rule)
for Union-All, Intersect, etc.
Below is more implementation-oriented:
As is shown here [1], as opposed to calling deriveType(), the code calls
validateOperands(). By doing so, the logic of overriding SqlOperator is
skipped.
However, if we call deriveType() here, the logic of overriding SqlOperator will
happen and validateOperands() will be called right afterwards [2].
[1]
https://github.com/apache/calcite/blob/4c7f5c20a04b4a4e736a16f801d8b5e6eded48cc/core/src/main/java/org/apache/calcite/sql/validate/SetopNamespace.java#L105
[2]
https://github.com/apache/calcite/blob/master/core/src/main/java/org/apache/calcite/sql/SqlOperator.java#L508
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