public static TableStats aggregateTableStat()

in tajo-catalog/tajo-catalog-common/src/main/java/org/apache/tajo/catalog/statistics/StatisticsUtil.java [89:147]
47 lines of code
19 McCabe index (conditional complexity)

  public static TableStats aggregateTableStat(List<TableStats> tableStatses) {
    TableStats aggregated = new TableStats();

    if(tableStatses == null || tableStatses.size() == 0 || tableStatses.get(0) == null)
      return aggregated;

    ColumnStats[] css = null;
    if (tableStatses.size() > 0) {
      for (TableStats ts : tableStatses) {
        // A TableStats cannot contain any ColumnStat if there is no output.
        // So, we should consider such a condition.
        if (ts.getColumnStats().size() > 0) {
          css = new ColumnStats[ts.getColumnStats().size()];
          for (int i = 0; i < css.length; i++) {
            css[i] = new ColumnStats(ts.getColumnStats().get(i).getColumn());
          }
          break;
        }
      }
    }

    for (TableStats ts : tableStatses) {
      // if there is empty stats
      if (ts.getColumnStats().size() > 0) {
        // aggregate column stats for each table
        for (int i = 0; i < ts.getColumnStats().size(); i++) {
          ColumnStats cs = ts.getColumnStats().get(i);
          if (cs == null) {
            LOG.warn("ERROR: One of column stats is NULL (expected column: " + css[i].getColumn() + ")");
            continue;
          }
          css[i].setNumDistVals(css[i].getNumDistValues() + cs.getNumDistValues());
          css[i].setNumNulls(css[i].getNumNulls() + cs.getNumNulls());
          if (!cs.minIsNotSet() && (css[i].minIsNotSet() ||
              css[i].getMinValue().compareTo(cs.getMinValue()) > 0)) {
            css[i].setMinValue(cs.getMinValue());
          }
          if (!cs.maxIsNotSet() && (css[i].maxIsNotSet() ||
              css[i].getMaxValue().compareTo(cs.getMaxValue()) < 0)) {
            css[i].setMaxValue(ts.getColumnStats().get(i).getMaxValue());
          }
        }
      }

      // aggregate table stats for each table
      aggregated.setNumRows(aggregated.getNumRows() + ts.getNumRows());
      aggregated.setNumBytes(aggregated.getNumBytes() + ts.getNumBytes());
      aggregated.setReadBytes(aggregated.getReadBytes() + ts.getReadBytes());
      aggregated.setNumBlocks(aggregated.getNumBlocks() + ts.getNumBlocks());
      aggregated.setNumShuffleOutputs(aggregated.getNumShuffleOutputs() + ts.getNumShuffleOutputs());
    }

    //aggregated.setAvgRows(aggregated.getNumRows() / tableStats.size());
    if (css != null) {
      aggregated.setColumnStats(Lists.newArrayList(css));
    }

    return aggregated;
  }