private void setSelectExpressions(
      Analysis analysis,
      QueryStatement queryStatement,
      List<Pair<Expression, String>> outputExpressions) {
    Set<Expression> selectExpressions = new LinkedHashSet<>();
    if (queryStatement.isOutputEndTime()) {
      selectExpressions.add(END_TIME_EXPRESSION);
    }
    for (Pair<Expression, String> outputExpressionAndAlias : outputExpressions) {
      Expression outputExpression = outputExpressionAndAlias.left;
      selectExpressions.add(outputExpression);
    }
    analysis.setSelectExpressions(selectExpressions);
  }
process select component for align by device.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/analyze/AnalyzeVisitor.java