presto-main/src/main/java/io/prestosql/execution/QueryStats.java/QueryStats/getSpilledDataSize
class QueryStats:    @JsonProperty
    public DataSize getSpilledDataSize()
    {
        return succinctBytes(operatorSummaries.stream()
                .mapToLong(stats -> stats.getSpilledDataSize().toBytes())
                .sum());
    }