[SERVER-79437] Providing an explicit atClusterTime with read concern snapshot in a transaction can violate snapshot isolation. Created: 27/Jul/23  Updated: 05/Sep/23  Resolved: 05/Sep/23

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

Type: Task Priority: Major - P3
Reporter: Kshitij Gupta Assignee: [DO NOT USE] Backlog - Sharding NYC
Resolution: Cannot Reproduce Votes: 0
Labels: sharding-nyc-subteam1
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Backports
Depends
Related
is related to SERVER-79766 TransactionRouter ignores atClusterTi... Backlog
Assigned Teams:
Sharding NYC
Backport Requested:
v7.1
Sprint: Sharding NYC 2023-09-04
Participants:
Linked BF Score: 105

 Description   

Updated title + more context from max.hirschhorn@mongodb.com's comment

While the manifestation a --dbg=on build variant would be the for mongos process to crash, in a production system, a client which had specified {readConcern: {level: "snapshot", atClusterTime: T1}} as the transaction read concern would have used a different timestamp T2 > T1 when starting the transaction on later participants. This would result in different participants using different read timestamps for the cross-shard transaction and violate snapshot isolation.



 Comments   
Comment by Randolph Tan [ 05/Sep/23 ]

Original crash has been reverted and atClusterTime is being ignored because of SERVER-79766

Generated at Thu Feb 08 06:40:58 UTC 2024 using Jira 9.7.1#970001-sha1:2222b88b221c4928ef0de3161136cc90c8356a66.