[SERVER-78296] Ban reads with readConcern snapshot on pre-images and change collection tables Created: 21/Jun/23  Updated: 29/Oct/23  Resolved: 01/Sep/23

Status: Closed
Project: Core Server
Component/s: None
Affects Version/s: None
Fix Version/s: 7.2.0-rc0

Type: Task Priority: Major - P3
Reporter: Josef Ahmad Assignee: Miquel Munoz (Inactive)
Resolution: Fixed Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Assigned Teams:
Storage Execution
Backwards Compatibility: Fully Compatible
Sprint: Execution EMEA Team 2023-08-21, Execution EMEA Team 2023-09-04
Participants:

 Description   

Pre-images and change collection tables prune old content using untimestamped truncates. A read establishing a snapshot at a point in time (PIT) may see data inconsistent with that PIT: data that should have been present at that PIT will be missing if it was truncated, since a non-truncated operation effectively overwrites history.

This behaviour is similar to capped collections before they replicated deletes explicitly (i.e. before SERVER-16049); we similarly banned reads with snapshot read concern on those (see SERVER-47574 and SERVER-47824).



 Comments   
Comment by Githook User [ 01/Sep/23 ]

Author:

{'name': 'Miquel Munoz', 'email': 'miquelmunozz@gmail.com', 'username': 'mimugara'}

Message: SERVER-78296 Ban reads with readConcern snapshot on pre-images and change collection tables
Branch: master
https://github.com/mongodb/mongo/commit/d7520f702397275fe1bbef22641de629929ba352

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