**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

{
        for (const auto & move_ttl : new_table_ttl.move_ttl)
        {
            if (!getDestinationForMoveTTL(move_ttl))
            {
                String message;
                if (move_ttl.destination_type == DataDestinationType::DISK)
                    message = "No such disk " + backQuote(move_ttl.destination_name) + " for given storage policy.";
                else
                    message = "No such volume " + backQuote(move_ttl.destination_name) + " for given storage policy.";
                throw Exception(message, ErrorCodes::BAD_TTL_EXPRESSION);
            }
        }
    }
}
void MergeTreeData::checkStoragePolicy(const StoragePolicyPtr & new_storage_policy) const
{
    const auto old_storage_policy = getStoragePolicy();
    old_storage_policy->checkCompatibleWith(new_storage_policy);
}
void MergeTreeData::MergingParams::check(const StorageInMemoryMetadata & metadata) const
{
    const auto columns = metadata.getColumns().getAllPhysical();
    if (!sign_column.empty() && mode != MergingParams::Collapsing && mode != MergingParams::VersionedCollapsing)
        throw Exception("Sign column for MergeTree cannot be specified in modes except Collapsing or VersionedCollapsing.",
                        ErrorCodes::LOGICAL_ERROR);
    if (!version_column.empty() && mode != MergingParams::Replacing && mode != MergingParams::VersionedCollapsing)
        throw Exception("Version column for MergeTree cannot be specified in modes except Replacing or VersionedCollapsing.",
                        ErrorCodes::LOGICAL_ERROR);
    if (!columns_to_sum.empty() && mode != MergingParams::Summing)