[SERVER-33831] Expire old history from `config.chunks` entries Created: 12/Mar/18  Updated: 27/Oct/23  Resolved: 21/Feb/23

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

Type: Task Priority: Major - P3
Reporter: Martin Neupauer Assignee: [DO NOT USE] Backlog - Sharding EMEA
Resolution: Works as Designed Votes: 0
Labels: ShardedTxn:FutureOptimizations, ShardedTxn:GlobalSnapshot, pm-564, sharding-common-backlog
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Assigned Teams:
Sharding EMEA
Participants:

 Description   

Today we simply purge any history older than 10 seconds as the storage engine does not support snapshots older than that. As part of this ticket, we should instead use the minimum timestamp across the cluster, which is known to the config server.



 Comments   
Comment by Pierlauro Sciarelli [ 21/Feb/23 ]

Closing the ticket as "works as designed" considering that:

  • The history array can only grow upon migrations
    AND
  • In the commit part of migrations the old history is pruned
    AND
  • Keeping some "old" history entries does not impact user experience in any way
Comment by Max Hirschhorn [ 02/Nov/22 ]

The behavior for when the placement history is expired from config.chunks documents changed as part of SERVER-48318 but I'm leaving this ticket open for Sharding EMEA to evaluate whether a different policy would be more appropriate given the work being done under PM-1939.

Comment by A. Jesse Jiryu Davis [ 20/May/20 ]

On second thought, this ticket might still be open. In SERVER-47785, I extended the history lifetime to min(10 seconds, minSnapshotHistoryWindowInSeconds). In SERVER-48318 I propose incorporating transactionLifetimeLimitSeconds too. But I don't know the exact intent of this ticket, so I can't say whether it will still be worth doing.

Comment by A. Jesse Jiryu Davis [ 18/May/20 ]

This will be obviated by SERVER-47785.

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