**Use case**

```
Received exception from server (version 21.11.1):
Code: 36. DB::Exception: Received from localhost:9000. DB::Exception: Wrong index name. Cannot find index `test_pentagram` to drop.. (BAD_ARGUMENTS)

github-explorer.ru-central1.internal :) ALTER TABLE hackernews DROP INDEX text_pentagram
```

It did not show me the typo.
*
      * PS. This can be corrected by making a pool that knows about which states of aggregate functions and in which order are put in it, and knows how to destroy them.
      * But this can hardly be done simply because it is planned to put variable-length strings into the same pool.
      * In this case, the pool will not be able to know with what offsets objects are stored.
      */
    const Aggregator * aggregator = nullptr;
    size_t keys_size{};  
    Sizes key_sizes;     
    
    Arenas aggregates_pools;
    Arena * aggregates_pool{};    
    /** Specialization for the case when there are no keys, and for keys not fitted into max_rows_to_group_by.
      */
    AggregatedDataWithoutKey without_key = nullptr;
    
    
    std::unique_ptr<AggregationMethodOneNumber<UInt8, AggregatedDataWithUInt8Key, false>>           key8;
    std::unique_ptr<AggregationMethodOneNumber<UInt16, AggregatedDataWithUInt16Key, false>>         key16;
    std::unique_ptr<AggregationMethodOneNumber<UInt32, AggregatedDataWithUInt64Key>>         key32;
    std::unique_ptr<AggregationMethodOneNumber<UInt64, AggregatedDataWithUInt64Key>>         key64;
    std::unique_ptr<AggregationMethodStringNoCache<AggregatedDataWithShortStringKey>>               key_string;
    std::unique_ptr<AggregationMethodFixedStringNoCache<AggregatedDataWithShortStringKey>>          key_fixed_string;
    std::unique_ptr<AggregationMethodKeysFixed<AggregatedDataWithUInt16Key, false, false, false>>  keys16;
    std::unique_ptr<AggregationMethodKeysFixed<AggregatedDataWithUInt32Key>>                   keys32;
    std::unique_ptr<AggregationMethodKeysFixed<AggregatedDataWithUInt64Key>>                   keys64;
    std::unique_ptr<AggregationMethodKeysFixed<AggregatedDataWithKeys128>>                   keys128;
    std::unique_ptr<AggregationMethodKeysFixed<AggregatedDataWithKeys256>>                   keys256;
    std::unique_ptr<AggregationMethodSerialized<AggregatedDataWithStringKey>>                serialized;
    std::unique_ptr<AggregationMethodOneNumber<UInt32, AggregatedDataWithUInt64KeyTwoLevel>> key32_two_level;
    std::unique_ptr<AggregationMethodOneNumber<UInt64, AggregatedDataWithUInt64KeyTwoLevel>> key64_two_level;