**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 (thread_parts.empty())
                            remaining_thread_parts.erase(thread_idx);
                    }
                    load_part(thread_part.first, thread_part.second);
                }
            });
        }
    }
    catch (...)
    {
        
        pool.wait();
        throw;
    }
    pool.wait();
    if (has_non_adaptive_parts && has_adaptive_parts && !settings->enable_mixed_granularity_parts)
        throw Exception(
            "Table contains parts with adaptive and non adaptive marks, but `setting enable_mixed_granularity_parts` is disabled",
            ErrorCodes::LOGICAL_ERROR);
    has_non_adaptive_index_granularity_parts = has_non_adaptive_parts;
    if (suspicious_broken_parts > settings->max_suspicious_broken_parts && !skip_sanity_checks)
        throw Exception(ErrorCodes::TOO_MANY_UNEXPECTED_DATA_PARTS,
            "Suspiciously many ({}) broken parts to remove.",
            suspicious_broken_parts);
    if (suspicious_broken_parts_bytes > settings->max_suspicious_broken_parts_bytes && !skip_sanity_checks)
        throw Exception(ErrorCodes::TOO_MANY_UNEXPECTED_DATA_PARTS,
            "Suspiciously big size ({}) of all broken parts to remove.",
            formatReadableSizeWithBinarySuffix(suspicious_broken_parts_bytes));
}
void MergeTreeData::loadDataPartsFromWAL(