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From StevenMPhillips <...@git.apache.org>
Subject [GitHub] drill pull request: DRILL-3232: Handle promoting writers and vecto...
Date Fri, 30 Oct 2015 23:40:10 GMT
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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