```sql
create table dat (blockNum Decimal(10,0), eventTimestamp DateTime64(9) ) 
Engine=MergeTree() primary key eventTimestamp;
insert into dat values (1, '2022-01-24 02:30:00.008122000');

CREATE DICTIONARY datDictionary
(
    `blockNum` Decimal(10, 0),
    `eventTimestamp` DateTime64(9)
)
PRIMARY KEY blockNum
SOURCE(CLICKHOUSE(TABLE 'dat'))
LIFETIME(MIN 0 MAX 1000)
LAYOUT(FLAT());

select * from datDictionary;
┌─blockNum─┬────────────────eventTimestamp─┐
│        1 │ 2022-01-24 02:30:00.008122000 │
└──────────┴───────────────────────────────┘

select count(*) from dat where eventTimestamp >= (select eventTimestamp from datDictionary);

Exception on client:
Code: 32. DB::Exception: Attempt to read after eof: while receiving packet from localhost:9000. (ATTEMPT_TO_READ_AFTER_EOF)

Connecting to localhost:9000 as user default.
Code: 210. DB::NetException: Connection refused (localhost:9000). (NETWORK_ERROR)
```

```sql
drop dictionary datDictionary;

CREATE DICTIONARY datDictionary
(
    `blockNum` Decimal(10, 0),
    `eventTimestamp` DateTime64(9)
)
PRIMARY KEY blockNum
SOURCE(CLICKHOUSE(TABLE 'dat'))
LIFETIME(MIN 0 MAX 1000)
LAYOUT(complex_key_hashed());

select count(*) from dat where eventTimestamp >= (select eventTimestamp from datDictionary);

Error on processing query: Code: 32. DB::Exception: Attempt to read after eof: while receiving packet from localhost:9000. (ATTEMPT_TO_READ_AFTER_EOF) (version 22.7.1.1054)

Connecting to localhost:9000 as user default.
Code: 210. DB::NetException: Connection refused (localhost:9000). (NETWORK_ERROR)
```

```sql
select * from datDictionary;
┌─blockNum─┬────────────────eventTimestamp─┐
│        1 │ 2022-01-24 02:30:00.008122000 │
└──────────┴───────────────────────────────┘

select dictGet('datDictionary', 'eventTimestamp', tuple(cast('1','Decimal(10,0)')));
Code: 407. DB::Exception: Received from localhost:9000. DB::Exception: Bad scale of decimal field. (DECIMAL_OVERFLOW)
```

{
    if (types.empty())
        return std::make_shared<DataTypeNothing>();
    if (types.size() == 1)
    {
        WhichDataType which(*types.begin());
        if (which.isNothing())
            return std::make_shared<DataTypeNothing>();
    #define DISPATCH(TYPE) \
        if (which.idx == TypeIndex::TYPE) \
            return std::make_shared<DataTypeNumber<TYPE>>(); /// NOLINT
        FOR_NUMERIC_TYPES(DISPATCH)
    #undef DISPATCH
        if (which.isString())
            return std::make_shared<DataTypeString>();
        return throwOrReturn<on_error>(types, "because cannot get common type by type indexes with non-simple types", ErrorCodes::NO_COMMON_TYPE);
    }
    if (types.contains(TypeIndex::String))
    {
        bool only_string = types.size() == 2 && types.contains(TypeIndex::Nothing);
        if (!only_string)
            return throwOrReturn<on_error>(types, "because some of them are String and some of them are not", ErrorCodes::NO_COMMON_TYPE);
        return std::make_shared<DataTypeString>();
    }
    auto numeric_type = getNumericType<on_error>(types);
    if (numeric_type)
        return numeric_type;
    return throwOrReturn<on_error>(types, "", ErrorCodes::NO_COMMON_TYPE);
}
DataTypePtr getLeastSupertypeOrString(const TypeIndexSet & types)