[SERVER-61712] Make ObjectId encoded in BSONColumn more efficient Created: 23/Nov/21  Updated: 29/Oct/23  Resolved: 30/Nov/21

Status: Closed
Project: Core Server
Component/s: None
Affects Version/s: None
Fix Version/s: 5.2.0

Type: Task Priority: Major - P3
Reporter: Henrik Edin Assignee: Henrik Edin
Resolution: Fixed Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Backwards Compatibility: Fully Compatible
Sprint: Execution Team 2021-11-29, Execution Team 2021-12-13
Participants:

 Description   

Currently, the least significant byte is timestamp and the second least counter. But because the counter is always incremented we essentially get a 2 byte change for both an update in timestamp or counter.

If we re-arrange to have the counter in the least significant byte we should be able to get a smaller 1 byte delta when only the counter is updated.



 Comments   
Comment by Githook User [ 30/Nov/21 ]

Author:

{'name': 'Henrik Edin', 'email': 'henrik.edin@mongodb.com', 'username': 'henrikedin'}

Message: SERVER-61712 Change ObjectId encoding for BSONColumn

Least significant counter byte is now least significant byte in encoding. Allows for smaller deltas when only counter is updated. Having timestamp as least significant does not help as counter is always updated.
Branch: master
https://github.com/mongodb/mongo/commit/1e754b14dcd3d904c7fbe1d7b719a5a7c9368365

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