presto-main/src/main/java/io/prestosql/execution/QueryStats.java/QueryStats/getWrittenPositions
class QueryStats:    @JsonProperty
    public long getWrittenPositions()
    {
        return operatorSummaries.stream()
                .filter(stats -> stats.getOperatorType().equals(TableWriterOperator.class.getSimpleName()))
                .mapToLong(OperatorStats::getInputPositions)
                .sum();
    }