Building the Presto Open Source Community – Ahana Round Table

Building the Presto Open Source Community – Ahana Round Table

In this round table moderated by Eric Kavanagh of The Bloor Group, panelists from Uber, Facebook, Ahana, and Alibaba will discuss all aspects of building a thriving open source community around PrestoDB including why Presto is so popular & the problems it solves, the open source model the foundation follows, why governance and transparency are so important to an open source community, and what the community looks for in open source projects.

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.