I have a table with one million rows of data. And It's schema is like:
```
create table redis_dictionary_test
(
	date String,
	id String,
	value Int64
)
engine = MergeTree()
partition by date
order by id
settings index_granularity = 8192;
```

I also inserted one million key-value pairs into Redis.
The dictionary is like:
```
create dictionary redis_dict
(
	date String,
	id String,
	value Int64
)
PRIMARY KEY date, id
SOURCE(REDIS(
	host '127.0.0.1'
	port 6379
	storage_type 'hash_map'
	db_index 0
))
LAYOUT(COMPLEX_KEY_DIRECT())
```
When I execute this query: `SELECT COUNT(DISTINCT dictGet('redis_dict', 'value', tuple(date, id))) FROM redis_dictionary_test;`, ClickHouse seems stuck. Progress was in this state: 122.88 thousand rows, 5.84 MB (1.20 million rows/s., 56.83 MB/s.)  12% about five minutes. Finally, I canceled query.

I am sure Redis is fine. Because I monitored Redis and it could accept read and write commands.

I also executed this query on 1000, 10000 and 100000 rows of data. They can return data normally.

What happened to ClickHouse? Where can I find out the reason?
const std::shared_ptr<Poco::Redis::Client> & client_,
            const RedisArray & keys_,
            const RedisStorageType & storage_type_,
            const DB::Block & sample_block,
            const size_t max_block_size_)
            : SourceWithProgress(sample_block)
            , client(client_), keys(keys_), storage_type(storage_type_), max_block_size{max_block_size_}
    {
        description.init(sample_block);
    }
    RedisSource::~RedisSource() = default;
    namespace
    {
        using ValueType = ExternalResultDescription::ValueType;
        template <typename T>
        inline void insert(IColumn & column, const String & string_value)
        {
            assert_cast<ColumnVector<T> &>(column).insertValue(parse<T>(string_value));
        }
        void insertValue(IColumn & column, const ValueType type, const Poco::Redis::BulkString & bulk_string)