public String getOutputSymbol() {
    return viewPath != null ? viewPath.getFullPath() : getOutputSymbolInternal();
  }
Get the output symbol of the expression.

<p>The hash code of the returned value will be the hash code of this object. See {@link
#hashCode()} and {@link #equals(Object)}.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/expression/Expression.java