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.

Common Sub Expression Optimization at Facebook

Common Sub Expression Optimization at Facebook

In complex analytics queries, we often see repeated expressions, for example parsing the same JSON column but extracting different fields, elaborate CASE statement with common predicates and different ones. Previously, Presto will compute the same expression many times as they appear in query. With common sub expression optimization, we would only evaluate the same expression once within the same project operator or filter operator. In our workload, we’ve seen 3x improvements on certain queries with expensive common sub expressions like JSON_PARSE. Microbenchmark also shows a consistent ~10% performance improvement for simple common sub-expressions like x + y. In this talk, we will talk about how this is implemented.