presto-main/src/main/java/io/prestosql/operator/StatisticsWriterOperator.java/StatisticsWriterOperator/addInput
class StatisticsWriterOperator:    @Override
    public void addInput(Page page)
    {
        requireNonNull(page, "page is null");
        checkState(state == State.RUNNING, "Operator is %s", state);

        for (int position = 0; position < page.getPositionCount(); position++) {
            computedStatisticsBuilder.add(getComputedStatistics(page, position));
        }
    }