Unnest is a common operation in Facebook’s daily Presto workload. It converts an ARRAY, MAP, or ROW into a flat relation. Its original implementation used deep copy all the time and was very inefficient. In Unnest Operator Performance Enhancement with Dictionary Blocks, the author improved the Unnest operator by up to 10x in CPU and…
Presto defines a connector API that allows Presto to query any data source that has a connector implementation. The existing connector API provides basic predicate pushdown functionality allowing connectors to perform filtering at the underlying data source. However, there are certain limitations with the existing predicate pushdown functionality that limits what connectors can do. The…