**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

{
    if (!partition_key.column_names.empty())
        return partition_key.expression->getRequiredColumnsWithTypes().getTypes();
    return {};
}
ExpressionActionsPtr MergeTreeData::getPrimaryKeyAndSkipIndicesExpression(const StorageMetadataPtr & metadata_snapshot) const
{
    return getCombinedIndicesExpression(metadata_snapshot->getPrimaryKey(), metadata_snapshot->getSecondaryIndices(), metadata_snapshot->getColumns(), global_context);
}
ExpressionActionsPtr MergeTreeData::getSortingKeyAndSkipIndicesExpression(const StorageMetadataPtr & metadata_snapshot) const
{
    return getCombinedIndicesExpression(metadata_snapshot->getSortingKey(), metadata_snapshot->getSecondaryIndices(), metadata_snapshot->getColumns(), global_context);
}
void MergeTreeData::checkPartitionKeyAndInitMinMax(const KeyDescription & new_partition_key)
{
    if (new_partition_key.expression_list_ast->children.empty())
        return;
    checkKeyExpression(*new_partition_key.expression, new_partition_key.sample_block, "Partition", allow_nullable_key);
    
    DataTypes minmax_idx_columns_types = getMinMaxColumnsTypes(new_partition_key);
    
    bool encountered_date_column = false;
    for (size_t i = 0; i < minmax_idx_columns_types.size(); ++i)
    {
        if (typeid_cast<const DataTypeDate *>(minmax_idx_columns_types[i].get()))
        {
            if (!encountered_date_column)
            {
                minmax_idx_date_column_pos = i;