[SERVER-34864] String-valued fields should not participate in schema change detection in ftdc Created: 07/May/18  Updated: 29/Oct/23  Resolved: 23/Aug/18

Status: Closed
Project: Core Server
Component/s: Diagnostics
Affects Version/s: None
Fix Version/s: 3.4.18, 3.6.9, 4.0.3, 4.1.3

Type: Bug Priority: Critical - P2
Reporter: Bruce Lucas (Inactive) Assignee: Mark Benvenuto
Resolution: Fixed Votes: 0
Labels: dev_tools
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Backports
Depends
Duplicate
is duplicated by SERVER-26464 Poor compression of diagnostic data w... Closed
Problem/Incident
Backwards Compatibility: Fully Compatible
Operating System: ALL
Backport Requested:
v4.0, v3.6, v3.4
Sprint: Platforms 2018-08-27
Participants:
Linked BF Score: 0

 Description   

There are various string-valued informational messages in serverStatus which may or may not be present depending on whether the condition they are informing about is present. If this presence of this field changes between samples this is detected by ftdc as a change in schema, causing a new chunk to be started. If this varies rapidly, e.g. every few seconds, then chunks are very short, causing a large decrease in compression efficiency, and therefore a decrease in ftdc retention. This is especially problematic because ftdc is likely to be important in diagnosing the issue.

Since string-valued fields don't contribute to ftdc, there's no reason that a change in the presence of a string valued field should be considered a schema change.



 Comments   
Comment by Githook User [ 19/Sep/18 ]

Author:

{'name': 'Mark Benvenuto', 'email': 'mark.benvenuto@mongodb.com', 'username': 'markbenvenuto'}

Message: SERVER-34864 FTDC should ignore irrelevant schema changes

(cherry picked from commit 078d6b49548d90880556af6f55e3baf8b4709917)
Branch: v3.6
https://github.com/mongodb/mongo/commit/7476443dd1282b83a9822833685917afcf7dcd2c

Comment by Githook User [ 18/Sep/18 ]

Author:

{'name': 'Mark Benvenuto', 'email': 'mark.benvenuto@mongodb.com', 'username': 'markbenvenuto'}

Message: SERVER-34864 FTDC should ignore irrelevant schema changes
Branch: v3.4
https://github.com/mongodb/mongo/commit/abdcd822a41b0e019279fae4a235b8c4a26c9668

Comment by Githook User [ 17/Sep/18 ]

Author:

{'name': 'Mark Benvenuto', 'email': 'mark.benvenuto@mongodb.com', 'username': 'markbenvenuto'}

Message: SERVER-34864 FTDC should ignore irrelevant schema changes

(cherry picked from commit 078d6b49548d90880556af6f55e3baf8b4709917)
Branch: v3.4
https://github.com/mongodb/mongo/commit/a845bcf20059b548ca8f1b4a51b8b4bd0512fa59

Comment by Githook User [ 17/Sep/18 ]

Author:

{'name': 'Mark Benvenuto', 'email': 'mark.benvenuto@mongodb.com', 'username': 'markbenvenuto'}

Message: SERVER-34864 FTDC should ignore irrelevant schema changes

(cherry picked from commit 078d6b49548d90880556af6f55e3baf8b4709917)
Branch: v4.0
https://github.com/mongodb/mongo/commit/95e012addfec1a6a0cb0ea656708a97b72b3848f

Comment by Githook User [ 23/Aug/18 ]

Author:

{'name': 'Mark Benvenuto', 'email': 'mark.benvenuto@mongodb.com', 'username': 'markbenvenuto'}

Message: SERVER-34864 FTDC should ignore irrelevant schema changes
Branch: master
https://github.com/mongodb/mongo/commit/078d6b49548d90880556af6f55e3baf8b4709917

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