[SERVER-73126] Integrate auto-merging within the balancer Created: 20/Jan/23  Updated: 29/Oct/23  Resolved: 20/Feb/23

Status: Closed
Project: Core Server
Component/s: None
Affects Version/s: None
Fix Version/s: 7.0.0-rc0

Type: Task Priority: Major - P3
Reporter: Pierlauro Sciarelli Assignee: Silvia Surroca
Resolution: Fixed Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Depends
depends on SERVER-65332 Remove the process splitting the clus... Closed
depends on SERVER-73987 Get rid of ClusterChunksResizePolicy Closed
is depended on by SERVER-73515 Make Automerger interval a configurab... Closed
Problem/Incident
causes SERVER-78569 Wait actively for chunks to be merged... Closed
Backwards Compatibility: Fully Compatible
Sprint: Sharding EMEA 2023-02-06, Sharding EMEA 2023-02-20
Participants:
Linked BF Score: 135

 Description   

Make the balancer rely on the command path introduced by SERVER-72278 in order to issue mergeAllChunksOnShard on shards.

The execution of the auto-merging path must be conditional on the value of the auto merger feature flag.
Auto-merging must happen:

  • When the balancer gets enabled
  • Every X hours after the last execution, configurable via a new server parameter defaulted to 24 hours. There is no need to track on disk the last time auto-merging happened, we could simply track an in-memory state cleared up when the balancer gets disabled.

The balancer should simply catch and ignore CommandNotFound errors that may be thrown in case of this super-improbable flow:

  1. Balancer checks FCV and feature flag, check passes
  2. FCV changes
  3. Shard binaries are replaced
  4. Balancer issues mergeAllChunksOnShard


 Comments   
Comment by Githook User [ 20/Feb/23 ]

Author:

{'name': 'Silvia Surroca', 'email': 'silvia.surroca@mongodb.com', 'username': 'silviasuhu'}

Message: SERVER-73126 Integrate auto-merging within the balancer
Branch: master
https://github.com/mongodb/mongo/commit/afb0f1ac441d9f1bd3b5a9c35dabd25c9133c93a

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