[DOCS-14772] [Server] Document the implications the state of the sharding metadata imposes on the serviceability of operations in a sharded cluster Created: 01/Sep/21  Updated: 08/Jan/24  Resolved: 01/Dec/23

Status: Closed
Project: Documentation
Component/s: manual, Server
Affects Version/s: None
Fix Version/s: 7.3 Targeted, Server_Docs_[20240108]

Type: Task Priority: Minor - P4
Reporter: Dmitry Ryabtsev Assignee: Joseph Dougherty
Resolution: Fixed Votes: 2
Labels: proactive, query, reopened, server-docs-bug-bash, sharding, triage
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Related
URL(s): https://www.mongodb.com/docs/manual/core/sharded-cluster-config-servers/
Participants:
Days since reply: 36 weeks ago

 Description   

At present the Server Documentation mentions very little on how the state of sharded cluster metadata view on individual shard members can affect whether a client operation succeeds or not.

I believe we need a new section introduced that elaborates on that topic (either under the `mongos` or under the Shards articles, but I guess the Config Server one could do as well).

What this section should reflect on is:

  • For an operation to succeed the view of the metadata on the specific shard member should be up-to-date (more precisely, the shard(s) and router issuing the request should have the same chunks view)
  • If the metadata is not up to date this can result in:
  •     The operation failing with the StaleConfig error
  •     Metadata refresh process being triggered
  • Updating the metadata can introduce additional operational latency
  • In case with secondary reads, metadata refresh can take prolonged time if a significant replication lag is present. It is recommended to use maxStalenessSeconds to minimize the impact of such a scenario


 Comments   
Comment by Ashley Brown [ 31/May/23 ]

Bumping priority due to linked HELP ticket. 

Comment by Sarah Olson [ 03/Nov/22 ]

Thanks for the feedback dmitry.ryabtsev@mongodb.com. We'll look into getting this addressed.

Comment by Education Bot [ 31/Oct/22 ]

Hello! This ticket has been closed due to inactivity. If you believe this ticket is still important, please reopen it and leave a comment to explain why. Thank you!

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