chunweilei commented on a change in pull request #1611: [CALCITE-3355] Deduce
whether CASE and COALESCE may produce NULL values
URL: https://github.com/apache/calcite/pull/1611#discussion_r352276577
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File path: core/src/main/java/org/apache/calcite/sql/fun/SqlCaseOperator.java
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@@ -230,14 +230,25 @@ private RelDataType inferTypeFromValidator(
SqlNodeList thenList = caseCall.getThenOperands();
ArrayList<SqlNode> nullList = new ArrayList<>();
List<RelDataType> argTypes = new ArrayList<>();
- for (SqlNode node : thenList) {
- argTypes.add(
- callBinding.getValidator().deriveType(
- callBinding.getScope(), node));
+
+ final SqlNodeList whenOperands = caseCall.getWhenOperands();
+ final RelDataTypeFactory typeFactory = callBinding.getTypeFactory();
+
+ final int size = thenList.getList().size();
+ for (int i = 0; i < size; i++) {
+ SqlNode node = thenList.get(i);
+ RelDataType type = callBinding.getValidator().deriveType(
+ callBinding.getScope(), node);
+ // We're sure that the type is not nullable if its kind is IS NOT NULL.
+ if (whenOperands.get(i).getKind() == SqlKind.IS_NOT_NULL &&
type.isNullable()) {
+ type = typeFactory.createTypeWithNullability(type, false);
Review comment:
I just find this fix is wrong. For instance,
for `case when name is not null then age else 20`, it should be nullable
when age is nullable.
I will spend more time on it.
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