Getting started with the new Redis HBO for Presto (Aug 30, 2023)

Getting started with the new Redis HBO for Presto (Aug 30, 2023)

Learn more about the new open-source Redis-based Historical Statistics Provider for Presto from Jay Narale, software engineer at Uber who built it. Redis is an open-source in-memory database that integrates with Presto through a dedicated connector. Now with a Redis history-based optimizer, you can enhance the efficiency and speed of query execution for Presto by using historical stats to generate optimized plans for your queries. Jay will cover how the Redis HBO utilizes the in-memory capabilities of Redis to store & analyze historical query execution data, which helps the optimizer make informed decisions about query planning and resource allocation based on the historical patterns of queries, leading to improved execution times and resource utilization.

Query Execution Optimization for Broadcast Join using Replicated-Reads Strategy – George Wang, Ahana

Query Execution Optimization for Broadcast Join using Replicated-Reads Strategy – George Wang, Ahana

Today presto supports broadcast join by having a worker to fetch data from a small data source to build a hash table and then sending the entire data over the network to all other workers for hash lookup probed by large data source. This can be optimized by a new query execution strategy as source data from small tables is pulled directly by all workers which is known as replicated reads from dimension tables. This feature comes with a nice caching property given that all worker nodes N are now participating in scanning the data from remote sources. The table scan operation for dimension tables is cacheable per all worker nodes. In addition, there will be better resource utilization because the presto scheduler can now reduce the number plan fragment to execute as the same workers run tasks in parallel within a single stage to reduce data shuffles.