[SERVER-33053] Allow unsharded connections to trigger EgressMetadataHook::readReplyMetadata through ShardingConnectionHook Created: 01/Feb/18  Updated: 12/Dec/23

Status: Backlog
Project: Core Server
Component/s: Sharding
Affects Version/s: None
Fix Version/s: None

Type: Task Priority: Major - P3
Reporter: Jack Mulrow Assignee: Backlog - Cluster Scalability
Resolution: Unresolved Votes: 0
Labels: PM-834, max-triage
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Related
related to SERVER-33017 Add metadata hook to update lastCommi... Closed
related to SERVER-36312 Re-enable atClusterTime selection alg... Closed
Assigned Teams:
Cluster Scalability
Participants:

 Description   

Currently, ShardingConnectionHook only attaches the reply metadata readers of its egressHook if _shardedConnections is true. For Global Point in Time reads, we want all connections from mongos to check for a "lastCommittedOpTime" field in responses, so we will need to allow for attaching some reply metadata hooks for unsharded connections as well, in particular those from the global connection pool.

Notably the replica set monitor currently uses a ScopedDBConnection to send isMaster commands, which uses unsharded connections from the globalConnPool, and it is important to the GPITR design that these commands track lastCommittedOpTimes.



 Comments   
Comment by Misha Tyulenev [ 10/Apr/18 ]

Currently storage can not support snapshot that will hold the window that is large enough for lastCommittedOpTime. Keep this task if the things will change by the PM-834 time.

Comment by Andy Schwerin [ 02/Feb/18 ]

Will this be a problem for commands that that are sent outside a sharded
cluster, like copydb or addShard?

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