[SERVER-33151] Refuse to start up mongod 4.0 unless all collections have UUIDs Created: 07/Feb/18  Updated: 29/Oct/23  Resolved: 26/Feb/18

Status: Closed
Project: Core Server
Component/s: Upgrade/Downgrade
Affects Version/s: None
Fix Version/s: 3.7.3

Type: Task Priority: Major - P3
Reporter: Maria van Keulen Assignee: Dianna Hohensee (Inactive)
Resolution: Fixed Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Depends
depends on SERVER-33246 Assign UUIDs to non-replicated collec... Closed
Backwards Compatibility: Fully Compatible
Sprint: Storage 2018-02-26
Participants:

 Description   

In 4.0, it is assumed all collections have UUIDs. To ensure no potential 3.4-3.6 related UUID assignment bugs carry over into 4.0 once a user upgrades, all collections should be checked on startup for UUIDs and mongod should fail to start up unless all collections have UUIDs.



 Comments   
Comment by Githook User [ 26/Feb/18 ]

Author:

{'email': 'dianna.hohensee@10gen.com', 'name': 'Dianna Hohensee', 'username': 'DiannaHohensee'}

Message: SERVER-33151 SERVER-33246 Refuse to start up mongod 4.0 unless all collections have UUIDs

Also assigns UUIDs to any non-replicated collection found to be missing its UUID.
Branch: master
https://github.com/mongodb/mongo/commit/bebdcf721eaa24fa589977bf48459a8cdd0fb2a2

Comment by Dianna Hohensee (Inactive) [ 22/Feb/18 ]

Ran into an issue where arbiters are upgraded to v4.0 and do not have UUIDs.

This is due to arbiters in v3.6 only ever setting FCV 3.4. Upgrading the replica set primary FCV to 3.6 is not replicated to an arbiter – arbiters don't replicate data! So a v3.6 arbiter doesn't have UUIDs on its non-replicated collections. And then gets upgraded to v4.0 and still doesn't have UUIDs, and this check breaks arbiters on that lack of UUIDs.

Therefore, since we also have the intention to automatically repair non-replicated collection UUIDs per SERVER-33246, SERVER-33246 will have to go in before or with this ticket.

Comment by Dianna Hohensee (Inactive) [ 09/Feb/18 ]

auto-fix non-replicated collection uuids on startup if needed.

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