Statistics
https://play.clickhouse.com/play?user=play#c2VsZWN0IAp0b1N0YXJ0T2ZIb3VyKGNoZWNrX3N0YXJ0X3RpbWUpIGFzIGQsCmNvdW50KCksICBncm91cFVuaXFBcnJheShwdWxsX3JlcXVlc3RfbnVtYmVyKSwgIGFueShyZXBvcnRfdXJsKQpmcm9tIGNoZWNrcyB3aGVyZSAnMjAyMi0wNi0wMScgPD0gY2hlY2tfc3RhcnRfdGltZSBhbmQgdGVzdF9uYW1lIGxpa2UgJyUwMjQ5MV9wYXJ0X2xvZ19oYXNfdGFibGVfdXVpZCUnIGFuZCB0ZXN0X3N0YXR1cyBpbiAoJ0ZBSUwnLCAnRkxBS1knKSBncm91cCBieSBkIG9yZGVyIGJ5IGQgZGVzYw==

Some times there are not output from requests.
{
    return NamesAndTypesList{
        NameAndTypePair("_part", std::make_shared<DataTypeString>()),
        NameAndTypePair("_part_index", std::make_shared<DataTypeUInt64>()),
        NameAndTypePair("_part_uuid", std::make_shared<DataTypeUUID>()),
        NameAndTypePair("_partition_id", std::make_shared<DataTypeString>()),
        NameAndTypePair("_partition_value", getPartitionValueType()),
        NameAndTypePair("_sample_factor", std::make_shared<DataTypeFloat64>()),
        NameAndTypePair("_part_offset", std::make_shared<DataTypeUInt64>()),
        LightweightDeleteDescription::FILTER_COLUMN,
    };
}
size_t MergeTreeData::getTotalMergesWithTTLInMergeList() const
{
    return getContext()->getMergeList().getMergesWithTTLCount();
}
void MergeTreeData::addPartContributionToDataVolume(const DataPartPtr & part)
{
    increaseDataVolume(part->getBytesOnDisk(), part->rows_count, 1);
}
void MergeTreeData::removePartContributionToDataVolume(const DataPartPtr & part)
{
    increaseDataVolume(-part->getBytesOnDisk(), -part->rows_count, -1);
}
void MergeTreeData::increaseDataVolume(ssize_t bytes, ssize_t rows, ssize_t parts)