It's pretty easy to imagine how to represent relational algebra expressions as a tree they are already structurally rooted trees where each operator has its.
Query Engines: Push vs Pull justinjaffray.com - get the latest breaking news, showbiz & celebrity photos, sport news & rumours, viral videos and top stories from justinjaffray.com Daily Mail and Mail on Sunday newspapers.
26 Apr 2021
People talk a lot about “pull” vs. “push” based query engines, and it’s
pretty obvious what that means colloquially, but some of the
details can be a bit hard to figure out.
Important people clearly have thought hard about this distinction, judging by this paragraph from Snowflake’s Sigmod paper:
Push-based execution refers to the fact that relational operators push their
results to their downstream operators, rather than waiting for these
operators to pull data (classic Volcano-style model). Push-based execution
improves cache efficiency, because it removes control flow logic from tight
loops. It also enables Snowflake to efficiently process DAG-shaped plans, as