Fix the bug of grout by column is null (apache#40)

fe/fe-core/src/main/java/org/apache/doris/analysis/Expr.java

@@ -1826,4 +1826,12 @@ public boolean isContainsClass(String className) {
  return false;
  }
 
+ /**
+ * For excute expr the result is nullable
+ * TODO: Now only SlotRef and LiteralExpr overwrite the method, each child of Expr should
+ * overwrite this method to plan correct
+ */
+ public boolean isNullable() {
+ return true;
+ }
 }

fe/fe-core/src/main/java/org/apache/doris/analysis/InlineViewRef.java

@@ -266,9 +266,8 @@ public TupleDescriptor createTupleDescriptor(Analyzer analyzer) throws AnalysisE
  }
 
  columnSet.add(colAlias);
- // TODO: inlineView threat all column is nullable to make sure query results are correct
- // we should judge column whether is nullable by selectItemExpr in the future
- columnList.add(new Column(colAlias, selectItemExpr.getType().getPrimitiveType(), true));
+ columnList.add(new Column(colAlias, selectItemExpr.getType().getPrimitiveType(),
+ selectItemExpr.isNullable()));
  }
  InlineView inlineView = (view != null) ? new InlineView(view, columnList) : new InlineView(getExplicitAlias(), columnList);
 

fe/fe-core/src/main/java/org/apache/doris/analysis/LiteralExpr.java

@@ -229,5 +229,10 @@ public boolean equals(Object obj) {
  }
  return this.compareLiteral(((LiteralExpr) obj)) == 0;
  }
+
+ @Override
+ public boolean isNullable() {
+ return this instanceof NullLiteral;
+ }
 }
 

fe/fe-core/src/main/java/org/apache/doris/analysis/SlotDescriptor.java

@@ -222,6 +222,7 @@ public int getSlotOffset() {
  * Initializes a slot by setting its source expression information
  */
  public void initFromExpr(Expr expr) {
+ setIsNullable(expr.isNullable());
  setLabel(expr.toSql());
  Preconditions.checkState(sourceExprs_.isEmpty());
  setSourceExpr(expr);

fe/fe-core/src/main/java/org/apache/doris/analysis/SlotRef.java

@@ -401,4 +401,9 @@ public static SlotRef read(DataInput in) throws IOException {
  slotRef.readFields(in);
  return slotRef;
  }
+
+ @Override
+ public boolean isNullable() {
+ return desc.getIsNullable();
+ }
 }