public Statement visitSelectStatement()

in iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/parser/ASTVisitor.java [1436:1574]
110 lines of code
32 McCabe index (conditional complexity)

  public Statement visitSelectStatement(IoTDBSqlParser.SelectStatementContext ctx) {
    QueryStatement queryStatement = new QueryStatement();

    // parse SELECT & FROM
    queryStatement.setSelectComponent(parseSelectClause(ctx.selectClause(), queryStatement));
    queryStatement.setFromComponent(parseFromClause(ctx.fromClause()));

    // parse INTO
    if (ctx.intoClause() != null) {
      queryStatement.setIntoComponent(parseIntoClause(ctx.intoClause()));
    }

    // parse WHERE
    if (ctx.whereClause() != null) {
      queryStatement.setWhereCondition(parseWhereClause(ctx.whereClause()));
    }

    // parse GROUP BY
    if (ctx.groupByClause() != null) {
      Set<String> groupByKeys = new HashSet<>();
      List<IoTDBSqlParser.GroupByAttributeClauseContext> groupByAttributes =
          ctx.groupByClause().groupByAttributeClause();
      for (IoTDBSqlParser.GroupByAttributeClauseContext groupByAttribute : groupByAttributes) {
        if (groupByAttribute.TIME() != null || groupByAttribute.interval != null) {
          if (groupByKeys.contains("COMMON")) {
            throw new SemanticException(GROUP_BY_COMMON_ONLY_ONE_MSG);
          }

          groupByKeys.add("COMMON");
          queryStatement.setGroupByTimeComponent(parseGroupByTimeClause(groupByAttribute));
        } else if (groupByAttribute.LEVEL() != null) {
          if (groupByKeys.contains("LEVEL")) {
            throw new SemanticException("duplicated group by key: LEVEL");
          }

          groupByKeys.add("LEVEL");
          queryStatement.setGroupByLevelComponent(parseGroupByLevelClause(groupByAttribute));
        } else if (groupByAttribute.TAGS() != null) {
          if (groupByKeys.contains("TAGS")) {
            throw new SemanticException("duplicated group by key: TAGS");
          }

          groupByKeys.add("TAGS");
          queryStatement.setGroupByTagComponent(parseGroupByTagClause(groupByAttribute));
        } else if (groupByAttribute.VARIATION() != null) {
          if (groupByKeys.contains("COMMON")) {
            throw new SemanticException(GROUP_BY_COMMON_ONLY_ONE_MSG);
          }

          groupByKeys.add("COMMON");
          queryStatement.setGroupByComponent(
              parseGroupByClause(groupByAttribute, WindowType.VARIATION_WINDOW));
        } else if (groupByAttribute.CONDITION() != null) {
          if (groupByKeys.contains("COMMON")) {
            throw new SemanticException(GROUP_BY_COMMON_ONLY_ONE_MSG);
          }

          groupByKeys.add("COMMON");
          queryStatement.setGroupByComponent(
              parseGroupByClause(groupByAttribute, WindowType.CONDITION_WINDOW));
        } else if (groupByAttribute.SESSION() != null) {
          if (groupByKeys.contains("COMMON")) {
            throw new SemanticException(GROUP_BY_COMMON_ONLY_ONE_MSG);
          }

          groupByKeys.add("COMMON");
          queryStatement.setGroupByComponent(
              parseGroupByClause(groupByAttribute, WindowType.SESSION_WINDOW));
        } else if (groupByAttribute.COUNT() != null) {
          if (groupByKeys.contains("COMMON")) {
            throw new SemanticException(GROUP_BY_COMMON_ONLY_ONE_MSG);
          }

          groupByKeys.add("COMMON");
          queryStatement.setGroupByComponent(
              parseGroupByClause(groupByAttribute, WindowType.COUNT_WINDOW));

        } else {
          throw new SemanticException("Unknown GROUP BY type.");
        }
      }
    }

    // parse HAVING
    if (ctx.havingClause() != null) {
      queryStatement.setHavingCondition(parseHavingClause(ctx.havingClause()));
    }

    // parse ORDER BY
    if (ctx.orderByClause() != null) {
      queryStatement.setOrderByComponent(
          parseOrderByClause(
              ctx.orderByClause(),
              ImmutableSet.of(OrderByKey.TIME, OrderByKey.DEVICE, OrderByKey.TIMESERIES)));
    }

    // parse FILL
    if (ctx.fillClause() != null) {
      queryStatement.setFillComponent(parseFillClause(ctx.fillClause()));
    }

    // parse ALIGN BY
    if (ctx.alignByClause() != null) {
      queryStatement.setResultSetFormat(parseAlignBy(ctx.alignByClause()));
    }

    if (ctx.paginationClause() != null) {
      // parse SLIMIT & SOFFSET
      if (ctx.paginationClause().seriesPaginationClause() != null) {
        if (ctx.paginationClause().seriesPaginationClause().slimitClause() != null) {
          queryStatement.setSeriesLimit(
              parseSLimitClause(ctx.paginationClause().seriesPaginationClause().slimitClause()));
        }
        if (ctx.paginationClause().seriesPaginationClause().soffsetClause() != null) {
          queryStatement.setSeriesOffset(
              parseSOffsetClause(ctx.paginationClause().seriesPaginationClause().soffsetClause()));
        }
      }

      // parse LIMIT & OFFSET
      if (ctx.paginationClause().rowPaginationClause() != null) {
        if (ctx.paginationClause().rowPaginationClause().limitClause() != null) {
          queryStatement.setRowLimit(
              parseLimitClause(ctx.paginationClause().rowPaginationClause().limitClause()));
        }
        if (ctx.paginationClause().rowPaginationClause().offsetClause() != null) {
          queryStatement.setRowOffset(
              parseOffsetClause(ctx.paginationClause().rowPaginationClause().offsetClause()));
        }
        if (canPushDownLimitOffsetToGroupByTime(queryStatement)) {
          pushDownLimitOffsetToTimeParameter(queryStatement, zoneId);
        }
      }
    }

    queryStatement.setUseWildcard(useWildcard);
    queryStatement.setLastLevelUseWildcard(lastLevelUseWildcard);
    return queryStatement;
  }