**How to reproduce**
Clickhouse server 20.13.1.5273
```
CREATE TABLE default.test
(
`key` UInt32,
`ts` DateTime CODEC(DoubleDelta, LZ4),
`db_time` DateTime DEFAULT now() COMMENT 'spout-ignore' CODEC(DoubleDelta, LZ4)
)
ENGINE = MergeTree
PARTITION BY toStartOfTenMinutes(db_time)
ORDER BY (key, ts)
TTL db_time + toIntervalHour(3)
SETTINGS index_granularity = 8192, merge_with_ttl_timeout = 3600, min_rows_for_compact_part = 1000000, min_bytes_for_compact_part = 200000000, in_memory_parts_enable_wal = 0;


INSERT INTO test(key, ts) SELECT number % 1000, now() + intDiv(number,1000) FROM numbers(500);

SELECT * FROM test;
500 rows in set. Elapsed: 0.003 sec.

DETACH TABLE test;

ATTACH TABLE test;

SELECT * FROM test;

0 rows in set. Elapsed: 0.002 sec.
```

**Expected behavior**
Clickhouse would flush parts on disk.
if (it == data_parts_by_info.end() || (*it).get() != part.get())
                throw Exception("Part " + part->name + " doesn't exist", ErrorCodes::LOGICAL_ERROR);
            part.reset();
            if (!((*it)->getState() == DataPartState::Outdated && it->unique()))
                return;
            modifyPartState(it, DataPartState::Deleting);
            part_to_delete = *it;
        }
        else
        {
            part_to_delete = std::move(part);
        }
    }
    try
    {
        part_to_delete->remove();
    }
    catch (...)
    {
        rollbackDeletingParts({part_to_delete});
        throw;
    }
    removePartsFinally({part_to_delete});
    LOG_TRACE(log, "Removed part {}", part_to_delete->name);
}
size_t MergeTreeData::getTotalActiveSizeInBytes() const
{
    return total_active_size_bytes.load(std::memory_order_acquire);
}
size_t MergeTreeData::getTotalActiveSizeInRows() const