# Presto 316 Documentation

## 12.91. Release 0.146

## General Changes

- Fix error in `map_concat()` when the second map is empty.
- Require at least 4096 file descriptors to run Presto.
- Support casting between map types.
- Add MongoDB Connector.

## Hive Changes

- Fix incorrect skipping of data in Parquet during predicate push-down.
- Fix reading of Parquet maps and lists containing nulls.
- Fix reading empty ORC file with `hive.orc.use-column-names` enabled.
- Fix writing to S3 when the staging directory is a symlink to a directory.
- Legacy authorization properties, such as `hive.allow-drop-table`, are now only enforced when `hive.security=none` is set, which is the default security system. Specifically, the `sql-standard` authorization system does not enforce these settings.

## Black Hole Changes

- Add support for `varchar(n)`.

## Cassandra Changes

- Add support for Cassandra 3.0.