[SERVER-57063] Ensure that config.collections exists upon configsvr startup Created: 19/May/21  Updated: 29/Oct/23  Resolved: 31/May/21

Status: Closed
Project: Core Server
Component/s: Sharding
Affects Version/s: 5.0.0
Fix Version/s: 5.0.0-rc1, 5.1.0-rc0

Type: Bug Priority: Major - P3
Reporter: Jordi Serra Torrens Assignee: Simon Gratzer (Inactive)
Resolution: Fixed Votes: 0
Labels: post-rc0, sharding-csrs-stepdown-only, sharding-wfbf-day
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Backports
Related
Backwards Compatibility: Fully Compatible
Operating System: ALL
Backport Requested:
v5.0
Participants:
Linked BF Score: 145

 Description   

On a brand new cluster, the config.collections collection on the configsvr is currently implicitly created when sharding the very first collection. There is a situation where attempting to refresh the CatalogCache (which does a Snapshot read on config.collections) from a CSRS node that has:
i) replicated the implicit creation of config.collections
ii) but not advanced its majority commit point to be inclusive of it
can fail with SnapshotUnavailable.
This situation will eventually resolve once the CSRS secondaries advance their majority commit point past the creation of config.collections.

To avoid this situation, we should make sure that config.collections exists upon configsvr startup.



 Comments   
Comment by Vivian Ge (Inactive) [ 06/Oct/21 ]

Updating the fixversion since branching activities occurred yesterday. This ticket will be in rc0 when it’s been triggered. For more active release information, please keep an eye on #server-release. Thank you!

Comment by Githook User [ 31/May/21 ]

Author:

{'name': 'Simon Graetzer', 'email': 'simon.gratzer@mongodb.com'}

Message: SERVER-57063 Ensure that config.collections exists upon configsvr startup (BACKPORT-9383)
Branch: v5.0
https://github.com/mongodb/mongo/commit/167c29ea15bccb6d58ca056d767ed27bd208f265

Comment by Githook User [ 31/May/21 ]

Author:

{'name': 'Simon Graetzer', 'email': 'simon.gratzer@mongodb.com'}

Message: SERVER-57063 Ensure that config.collections exists upon configsvr startup
Branch: master
https://github.com/mongodb/mongo/commit/a10eaa3cc0e78d4ab1cd2f57b61a1e5e9568e192

Comment by Simon Gratzer (Inactive) [ 27/May/21 ]

https://mongodbcr.appspot.com/773440001/

Comment by Jordi Serra Torrens [ 19/May/21 ]

A proposal is to create config.collections locally here. Note that here, similarly, by building indexes on config.chunks we are effectively already creating the config.chunks collections.

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