Buzz Chronicles
Follow
  • Home
  • Threads
    • Daily Charts
    • Most Popular
    • Most Recent
  • Authors
  • Categories
    • Life
    • Tech
    • Culture
    • Politics
    • Society
    • Fun
    • See All Categories
  • About

Authors Andy Pavlo

7 days 30 days All time Recent Popular
Andy Pavlo
Andy Pavlo
@andy_pavlo
If you're interested in DB internals, stop what you're doing and watch @CMUDB Quarantine Talk from Nico+Cesar about @SQLServer's Cascades query optimizer: https://t.co/FCdsbHHEaD

Many talks this semester were good. This one is the best. My thread provides key takeaways

[6:50] Microsoft hired Goetz Graffe in the 1990s to help them rewrite original Sybase optimizer into Cascades. This framework is now used across all MSFT DB products (@SQLServer, @cosmosdb, @Azure_Synapse).

[14:43] The optimizer checks whether it has stats it will need before cost-based search. If not, it blocks planning until the DBMS generates them. This is different than other approaches we saw this semester where DBMS says "we'll do it live!" with whatever stats are available.

[21:05] Their Cascades' search starts small/simple and then they make decision on the fly whether to expand search based on the expected query runtime and performance benefit from more search.

[26:33] They explicitly have a property for Halloween Problem. Operators specify whether they protect from it and then optimizer ensures property is satisfied. This is mindblowing. I have never thought about using the optimizer for this but it makes sense.
INTERNET
  • Page 1 of 1
How does it work?
  • 💬 Reply to a thread with "@buzz_chronicles save" or "@buzz_chronicles save as category"
    🤖 Our bot will send you a link to your own folder on Buzz Chronicles. The thread will be saved in a form of an easy-to-read article
    📁 All your saved threads will be available at buzzchronicles.com/your_twitter_handle
Buzz Chronicles
  • Explore
  • Threads
  • Daily Charts
  • Authors
  • Categories
  • About
  • Terms of Service

Copyright © 2021 Buzz Chronicles - All right reserved