[HN Gopher] Challenges in join optimization
       ___________________________________________________________________
        
       Challenges in join optimization
        
       Author : HermitX
       Score  : 29 points
       Date   : 2026-01-21 17:03 UTC (5 hours ago)
        
 (HTM) web link (www.starrocks.io)
 (TXT) w3m dump (www.starrocks.io)
        
       | j-pb wrote:
       | Whenever I read join optimisation articles in SQL based systems
       | it feels... off.
       | 
       | There is too much heuristic fiddling involved, and way too many
       | niche algorithms that get cobbled together with an optimiser.
       | 
       | As if we're missing the theory to actually solve the stuff, so
       | we're instead hobbling along by covering as many corner cases as
       | we can, completely missing some elegant and profound beauty.
        
         | Sesse__ wrote:
         | This post certainly has too much heuristic fiddling! Instead of
         | a coherent framework, it takes a bunch of second-rate
         | heuristics and tries to use... well, all of them. "Generate at
         | most ten plans of this and one of that"? It also has pages and
         | pages talking about the easier parts, for some reason (like
         | maintaining maps, or that a Cartesian product and an inner join
         | are basically the same thing), and things that are just wrong
         | (like "prefer antijoins", which is bad in most databases since
         | they are less-reorderable than almost any other join; not that
         | you usually have much of a choice in choosing the join type in
         | the first place).
         | 
         | There _are_ tons of corner cases that you need to address since
         | there are some super-hard problems in there (in particular,
         | robust cardinality estimation of join outputs is a problem so
         | hard that most of academia barely wants to touch it, despite
         | its huge importance), but it doesn't need to be this bad.
        
       | Ibrahim26 wrote:
       | Yeah Bro I'm a student, so let me learn something new .
        
       ___________________________________________________________________
       (page generated 2026-01-21 23:00 UTC)