**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.
deduplicate,
                    deduplicate_by_columns,
                    &disable_reason,
                    local_context->getSettingsRef().optimize_skip_merged_partitions))
            {
                constexpr const char * message = "Cannot OPTIMIZE table: {}";
                if (disable_reason.empty())
                    disable_reason = "unknown reason";
                LOG_INFO(log, message, disable_reason);
                if (local_context->getSettingsRef().optimize_throw_if_noop)
                    throw Exception(ErrorCodes::CANNOT_ASSIGN_OPTIMIZE, message, disable_reason);
                return false;
            }
        }
    }
    else
    {
        String partition_id;
        if (partition)
            partition_id = getPartitionIDFromQuery(partition, local_context);
        if (!merge(
                true,
                partition_id,
                final,
                deduplicate,
                deduplicate_by_columns,
                &disable_reason,
                local_context->getSettingsRef().optimize_skip_merged_partitions))
        {
            constexpr const char * message = "Cannot OPTIMIZE table: {}";