[SERVER-85024] Histogram-based cardinality estimation for conjunctions Created: 24/Aug/21  Updated: 13/Jan/24  Resolved: 18/Oct/21

Status: Closed
Project: Core Server
Component/s: None
Affects Version/s: None
Fix Version/s: None

Type: Task Priority: Major - P3
Reporter: Nicholas Zolnierz Assignee: Backlog - Query Optimization
Resolution: Won't Fix Votes: 0
Labels: next-stats-spike-candidate
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Assigned Teams:
Query Optimization
Participants:

 Description   

There are several options to explore here, and its not clear of the advantages of each:

  • Option 0: simple scaling factor
  • Option 1: use set of samples to estimate correlation rather than simple scaling factor
  • Option 2: exponential backoff
  • Option 3: Use NDVs for each field as a weighting mechanism (not sure if this is the approach described by Milena or not)
  • Option 4: Multi-field histograms (would require equality on prefix predicate?)

The 4th option is out of scope for this ticket but would be worth considering down the line.



 Comments   
Comment by Charlie Swanson [ 18/Oct/21 ]

We did not have time to pursue this during the spike so I am closing it out. I invented a new "next-stats-spike-candidate" label if we want to find things like this later.

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