[SERVER-68377] Avoid reading the special dense column if reading a known to be dense path Created: 27/Jul/22  Updated: 29/Oct/23  Resolved: 21/Dec/22

Status: Closed
Project: Core Server
Component/s: None
Affects Version/s: None
Fix Version/s: 6.3.0-rc0

Type: Task Priority: Major - P3
Reporter: Irina Yatsenko (Inactive) Assignee: Dianna Hohensee (Inactive)
Resolution: Fixed Votes: 0
Labels: pm2646-m5
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Backwards Compatibility: Fully Compatible
Sprint: QE 2022-11-14, QE 2022-11-28, QE 2022-12-12, QE 2022-12-26
Participants:

 Description   

Currently, the column_scan stage always reads the special dense column in absence of filters. There are two issues to consider:

  1. In some cases (e.g. if "_id" column is also being read) reading the dense column isn't needed for correctness and we should avoid it.
  2. Should the decision to use the dense column belong to the scan_stage or to its clients?


 Comments   
Comment by Githook User [ 21/Dec/22 ]

Author:

{'name': 'Dianna Hohensee', 'email': 'dianna.hohensee@mongodb.com', 'username': 'DiannaHohensee'}

Message: SERVER-68377 Skip creating a dense column cursor during a column scan when an _id column cursor (also dense) is present
Branch: master
https://github.com/mongodb/mongo/commit/42667e3c762bd83d700696ec4635e41fb8471c0f

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