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

Some times there are not output from requests.
{
    DataPartsVector res;
    if (const auto * txn = local_context->getCurrentTransaction().get())
    {
        res = getDataPartsVectorForInternalUsage({DataPartState::Active, DataPartState::Outdated}, lock);
        filterVisibleDataParts(res, txn->getSnapshot(), txn->tid);
    }
    else
    {
        res = getDataPartsVectorForInternalUsage({DataPartState::Active}, lock);
    }
    return res;
}
MergeTreeData::DataPartsVector MergeTreeData::getVisibleDataPartsVector(const MergeTreeTransactionPtr & txn) const
{
    DataPartsVector res;
    if (txn)
    {
        res = getDataPartsVectorForInternalUsage({DataPartState::Active, DataPartState::Outdated});
        filterVisibleDataParts(res, txn->getSnapshot(), txn->tid);
    }
    else
    {
        res = getDataPartsVectorForInternalUsage();
    }
    return res;
}
MergeTreeData::DataPartsVector MergeTreeData::getVisibleDataPartsVector(CSN snapshot_version, TransactionID current_tid) const