```sql
SELECT count()
FROM 
(
    SELECT number
    FROM numbers_mt(100000000)
    ORDER BY number DESC
    LIMIT 100
    UNION ALL
    SELECT number
    FROM numbers_mt(100000000)
    ORDER BY number DESC
    LIMIT 100
    UNION ALL
    SELECT number
    FROM numbers_mt(100000000)
    ORDER BY number DESC
    LIMIT 100
)


SET experimental_use_processors = 0;
-- 1 rows in set. Elapsed: 1.581 sec. Processed 300.00 million rows, 2.40 GB (189.78 million rows/s., 1.52 GB/s.) 

SET experimental_use_processors = 1;
-- 1 rows in set. Elapsed: 3.569 sec. Processed 300.00 million rows, 2.40 GB (84.06 million rows/s., 672.50 MB/s.) 
```

Similar for MergeTree:

```sql
create table test engine=MergeTree order by tuple() as select * from numbers(30000000);

select count() from (select number from test group by number order by number limit 10 union all select number from test group by number order by number limit 10);

set experimental_use_processors=0;
-- Elapsed: 2.664 sec

set experimental_use_processors=1;
-- Elapsed: 3.656 sec
```
void setSinks(const ProcessorGetterWithStreamKind & getter);
    
    void addDefaultTotals();
    
    void addTotals(ProcessorPtr source);
    
    void dropTotalsAndExtremes();
    
    void addDelayedStream(ProcessorPtr source);
    
    bool hasMixedStreams() const { return has_resize || hasMoreThanOneStream(); }
    
    void resize(size_t num_streams, bool force = false, bool strict = false);
    void enableQuotaForCurrentStreams();
    
    
    void unitePipelines(std::vector<std::unique_ptr<QueryPipeline>> pipelines, const Block & common_header);
    PipelineExecutorPtr execute();
    size_t getNumStreams() const { return streams.size(); }
    bool hasMoreThanOneStream() const { return getNumStreams() > 1; }
    bool hasTotals() const { return totals_having_port != nullptr; }