Happy Friday! A few weeks ago I began looking into what it would take to upgrade to the latest version of Calcite (Pinot dependency that's responsible for parsing SQL) and figured that it would be helpful to have a deep understanding in how SQL is parsed and executed. Searching through the design docs and GH issues I found the following resources that may be relevant to understanding Query Processing: • https://github.com/apache/pinot/issues/4219 • https://docs.google.com/document/d/1uNIq0cybUtVtdtJ38-4ewFNEQorbg-2KYr-CMSj6H_8/edit?usp=sharing • https://cwiki.apache.org/confluence/display/PINOT/Query+Processing If you have any other resources, please do share them in a new thread. Thanks!

cc: @Jackie who is also looking into calcite upgrade