[SERVER-53609] lastCommittedTransaction section causes frequent schema changes that limit FTDC retention Created: 06/Jan/21  Updated: 29/Oct/23  Resolved: 08/Jan/21

Status: Closed
Project: Core Server
Component/s: Diagnostics, Replication
Affects Version/s: None
Fix Version/s: 4.9.0, 4.0.23, 4.4.4, 4.2.13

Type: Bug Priority: Major - P3
Reporter: Bruce Lucas (Inactive) Assignee: Jason Chan
Resolution: Fixed Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Backports
Related
is related to SERVER-40298 Track transaction size on 4.0 Closed
is related to SERVER-40372 Track transaction size on 4.2+ Closed
Backwards Compatibility: Fully Compatible
Operating System: ALL
Backport Requested:
v4.4, v4.2, v4.0
Sprint: Repl 2021-01-11
Participants:

 Description   

serverStatus.transactions.lastCommittedTransaction.writeConcern records the write concern of the last committed transaction. This subdocument does not have a fixed schema: it may be empty or not, and the w field may be either a string or a number. This causes frequent schema changes for FTDC, and that can severely limit FTDC retention.

A record of the last committed transaction has limited diagnostic value, so the best solution may be to omit the entire lastCommittedTransaction section from FTDC.



 Comments   
Comment by Githook User [ 05/Feb/21 ]

Author:

{'name': 'Jason Chan', 'email': 'jason.chan@mongodb.com', 'username': 'jasonjhchan'}

Message: SERVER-53609 Filter out serverStatus.transactions.lastCommittedTransaction from FTDC

(cherry picked from commit 3e5fc29b410b4a0e999f190de5f035e3119f6565)
(cherry picked from commit 97f5866b751246f4b035ebe1cff7ac371e2430fa)
Branch: v4.0
https://github.com/mongodb/mongo/commit/7883bfe8349b4439f55fd8d4199fab1455b6d67d

Comment by Githook User [ 04/Feb/21 ]

Author:

{'name': 'Jason Chan', 'email': 'jason.chan@mongodb.com', 'username': 'jasonjhchan'}

Message: SERVER-53609 Filter out serverStatus.transactions.lastCommittedTransaction from FTDC

(cherry picked from commit 3e5fc29b410b4a0e999f190de5f035e3119f6565)
Branch: v4.2
https://github.com/mongodb/mongo/commit/97f5866b751246f4b035ebe1cff7ac371e2430fa

Comment by Githook User [ 27/Jan/21 ]

Author:

{'name': 'Jason Chan', 'email': 'jason.chan@mongodb.com', 'username': 'jasonjhchan'}

Message: SERVER-53609 Filter out serverStatus.transactions.lastCommittedTransaction from FTDC

(cherry picked from commit 3e5fc29b410b4a0e999f190de5f035e3119f6565)
Branch: v4.4
https://github.com/mongodb/mongo/commit/6f74f6f0e9f85d55f7c9b5d217d583f9bba308db

Comment by Ian Whalen (Inactive) [ 09/Jan/21 ]

Author:

{'username': u'evrg-bot-webhook', 'name': u'Jason Chan', 'email': u'jason.chan@mongodb.com'}

Message:SERVER-53609 Filter out serverStatus.transactions.lastCommittedTransaction from FTDC
Branch:master
https://github.com/mongodb/mongo/commit/3e5fc29b410b4a0e999f190de5f035e3119f6565

Comment by Judah Schvimer [ 06/Jan/21 ]

SERVER-47528 is a similar example of removing a section from FTDC that took up too much space (a slightly different motivation but same goal).

Comment by Bruce Lucas (Inactive) [ 06/Jan/21 ]

I've assigned this to the replication team to start since that's where the section originated via SERVER-40298 and SERVER-40372, but I suspect this might ultimately need work both in replication and in ftdc code.

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