[SERVER-36971] Rollback progress message can report confusing numbers Created: 03/Sep/18  Updated: 06/Dec/22  Resolved: 15/Jan/20

Status: Closed
Project: Core Server
Component/s: Replication
Affects Version/s: 3.2.21, 3.4.17, 3.6.6, 4.0.2, 4.1.3
Fix Version/s: None

Type: Bug Priority: Minor - P4
Reporter: Dmitry Ryabtsev Assignee: Backlog - Replication Team
Resolution: Won't Fix Votes: 0
Labels: neweng, replication-rollbackviarefetch
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Assigned Teams:
Replication
Operating System: ALL
Participants:
Case:

 Description   

This has been observed on v3.6.6:

2018-08-31T09:45:58.682+0000 I ROLLBACK [rsBackgroundSync] 1005 delete and 0 update operations processed out of 4 total operations.

As can be seen in this case, the actual number of operations processed here is much higher than the estimated total number of operations.



 Comments   
Comment by Tess Avitabile (Inactive) [ 15/Jan/20 ]

Closing as Won't Fix, since this bug only affects rollbackViaRefetch.

Comment by Judah Schvimer [ 18/Sep/18 ]

This bug exists in all versions of rollback via refetch and not rollback to a timestamp, but in 3.4 and 3.2 it's namespaces rather than UUIDs.

Comment by Judah Schvimer [ 18/Sep/18 ]

Here's the code that creates this log:

                log() << deletes << " delete and " << updates
                      << " update operations processed out of " << goodVersions.size()
                      << " total operations.";

goodVersions is a map from UUID -> doc id -> doc. Thus this is actually logging the number of UUIDs touched, not the number of operations.

This is another log that is wrong:

    log() << "Finished refetching documents. Total size of documents refetched: "
          << goodVersions.size();

Comment by Tess Avitabile (Inactive) [ 04/Sep/18 ]

Please find out whether this happens with recover to timestamp or only rollbackViaRefetch.

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