**Describe the bug**

I have a table like:

```
CREATE TABLE test (
    time DateTime64(3)
    ...
) ENGINE = MergeTree()
PARTITION BY toStartOfInterval(time, INTERVAL 1 HOUR)
...
```

But when I search in `system.parts` it does not appear to have the `min/max` columns appropriately set?

```
partition:                             2020-06-01 01:00:00
min_date:                              1970-01-01
max_date:                              1970-01-01
min_time:                              1970-01-01 00:00:00
max_time:                              1970-01-01 00:00:00
```

I assume that if these were correctly set, doing a `select toStartOfInterval(time, interval 1 day), count()` type query would be pretty instant rather than trying to scan everything? I am guessing this is due to the `DateTime64` type in use?

Clickhouse 20.11.3.3

{
    return global_context.getStoragePolicy(getSettings()->storage_policy);
}
static void checkKeyExpression(const ExpressionActions & expr, const Block & sample_block, const String & key_name, bool allow_nullable_key)
{
    for (const auto & action : expr.getActions())
    {
        if (action.node->type == ActionsDAG::ActionType::ARRAY_JOIN)
            throw Exception(key_name + " key cannot contain array joins", ErrorCodes::ILLEGAL_COLUMN);
        if (action.node->type == ActionsDAG::ActionType::FUNCTION)
        {
            IFunctionBase & func = *action.node->function_base;
            if (!func.isDeterministic())
                throw Exception(key_name + " key cannot contain non-deterministic functions, "
                    "but contains function " + func.getName(),
                    ErrorCodes::BAD_ARGUMENTS);
        }
    }
    for (const ColumnWithTypeAndName & element : sample_block)
    {
        const ColumnPtr & column = element.column;
        if (column && (isColumnConst(*column) || column->isDummy()))
            throw Exception{key_name + " key cannot contain constants", ErrorCodes::ILLEGAL_COLUMN};
        if (!allow_nullable_key && element.type->isNullable())
            throw Exception{key_name + " key cannot contain nullable columns", ErrorCodes::ILLEGAL_COLUMN};
    }
}
void MergeTreeData::checkProperties(