# Presto 316 Documentation

## 12.114. Release 0.130

## General Changes

- Fix a performance regression in `GROUP BY` and `JOIN` queries when the length of the keys is between 16 and 31 bytes.
- Add `map_concat()` function.
- Performance improvements for filters, projections and dictionary encoded data. This optimization is turned off by default. It can be configured via the `optimizer.columnar-processing-dictionary` config property or the `columnar_processing_dictionary` session property.
- Improve performance of aggregation queries with large numbers of groups.
- Improve performance for queries that use ARRAY type.
- Fix querying remote views in MySQL and PostgreSQL connectors.