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?
}
}
namespace DB
{
    class RedisSource final : public SourceWithProgress
    {
    public:
        using RedisArray = Poco::Redis::Array;
        using RedisBulkString = Poco::Redis::BulkString;
        RedisSource(
                const std::shared_ptr<Poco::Redis::Client> & client_,
                const Poco::Redis::Array & keys_,
                const RedisStorageType & storage_type_,
                const Block & sample_block,
                const size_t max_block_size);
        ~RedisSource() override;
        String getName() const override { return "Redis"; }
    private:
        Chunk generate() override;
        std::shared_ptr<Poco::Redis::Client> client;
        Poco::Redis::Array keys;
        RedisStorageType storage_type;
        const size_t max_block_size;
        ExternalResultDescription description;
        size_t cursor = 0;
        bool all_read = false;
    };
}