Github user StevenMPhillips commented on a diff in the pull request:
https://github.com/apache/drill/pull/207#discussion_r43563065
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/expr/ExpressionTreeMaterializer.java
---
@@ -323,23 +454,50 @@ public LogicalExpression
visitIfExpression(IfExpression ifExpr, FunctionLookupCo
MinorType thenType =
conditions.expression.getMajorType().getMinorType();
MinorType elseType = newElseExpr.getMajorType().getMinorType();
-
- // Check if we need a cast
- if (thenType != elseType && !(thenType == MinorType.NULL || elseType
== MinorType.NULL)) {
-
- MinorType leastRestrictive =
TypeCastRules.getLeastRestrictiveType((Arrays.asList(thenType, elseType)));
- if (leastRestrictive != thenType) {
- // Implicitly cast the then expression
+ boolean hasUnion = thenType == MinorType.UNION || elseType ==
MinorType.UNION;
+ if (unionTypeEnabled) {
+ if (thenType != elseType && !(thenType == MinorType.NULL ||
elseType == MinorType.NULL)) {
+
+ MinorType leastRestrictive = MinorType.UNION;
+ MajorType.Builder builder =
MajorType.newBuilder().setMinorType(MinorType.UNION).setMode(DataMode.OPTIONAL);
+ if (thenType == MinorType.UNION) {
+ for (MinorType subType :
conditions.expression.getMajorType().getSubTypeList()) {
+ builder.addSubType(subType);
+ }
+ } else {
+ builder.addSubType(thenType);
+ }
+ if (elseType == MinorType.UNION) {
+ for (MinorType subType :
newElseExpr.getMajorType().getSubTypeList()) {
+ builder.addSubType(subType);
+ }
+ } else {
+ builder.addSubType(elseType);
+ }
+ MajorType unionType = builder.build();
conditions = new IfExpression.IfCondition(newCondition,
- addCastExpression(conditions.expression,
newElseExpr.getMajorType(), functionLookupContext, errorCollector));
- } else if (leastRestrictive != elseType) {
- // Implicitly cast the else expression
- newElseExpr = addCastExpression(newElseExpr,
conditions.expression.getMajorType(), functionLookupContext, errorCollector);
- } else {
- /* Cannot cast one of the two expressions to make the output
type of if and else expression
- * to be the same. Raise error.
- */
- throw new DrillRuntimeException("Case expression should have
similar output type on all its branches");
+ addCastExpression(conditions.expression, unionType,
functionLookupContext, errorCollector));
+ newElseExpr = addCastExpression(newElseExpr, unionType,
functionLookupContext, errorCollector);
+ }
+
+ } else {
+ // Check if we need a cast
+ if (thenType != elseType && !(thenType == MinorType.NULL ||
elseType == MinorType.NULL)) {
+
+ MinorType leastRestrictive =
TypeCastRules.getLeastRestrictiveType((Arrays.asList(thenType, elseType)));
+ if (leastRestrictive != thenType) {
+ // Implicitly cast the then expression
+ conditions = new IfExpression.IfCondition(newCondition,
+ addCastExpression(conditions.expression,
newElseExpr.getMajorType(), functionLookupContext, errorCollector));
+ } else if (leastRestrictive != elseType) {
+ // Implicitly cast the else expression
+ newElseExpr = addCastExpression(newElseExpr,
conditions.expression.getMajorType(), functionLookupContext, errorCollector);
+ } else {
+ /* Cannot cast one of the two expressions to make the output
type of if and else expression
+ * to be the same. Raise error.
+ */
+ throw new DrillRuntimeException("Case expression should have
similar output type on all its branches");
--- End diff --
I don't think this is a problem. In this case, the case statement will not
coerce to a type unless one of the branches output is that type. So as long as
there is no Union type in the input, there won't be a union in the output.
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