[SERVER-77704] Replace MurmurHash3 with absl::Hash if possible in ReshardingOplogBatchPreparer::_appendCrudOpToWriterVector Created: 01/Jun/23  Updated: 31/Oct/23  Resolved: 31/Oct/23

Status: Closed
Project: Core Server
Component/s: None
Affects Version/s: None
Fix Version/s: 7.2.0-rc0

Type: Task Priority: Major - P3
Reporter: Dan Larkin-York Assignee: Ivan Fefer
Resolution: Fixed Votes: 0
Labels: neweng
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Assigned Teams:
Sharding NYC
Backwards Compatibility: Fully Compatible
Sprint: QE 2023-11-13
Participants:

 Description   

MurmurHash3 is a pretty old hash function that's slow and produces low-quality hashes compared to modern alternatives like absl::Hash (CityHash). We want to replace any uses of MurmurHash3 which are for in-memory use only, as we expect this to yield quick perf wins. Hash values that are persisted to disk across restarts or sent across the network between servers are likely unsafe to change, and should be annotated with a clear explanation for why the usage requires a stable hash computation.



 Comments   
Comment by Githook User [ 30/Oct/23 ]

Author:

{'name': 'Ivan Fefer', 'email': 'ivan.fefer@mongodb.com', 'username': 'Fefer-Ivan'}

Message: SERVER-77704 Remove murmur3 use in resharding
Branch: master
https://github.com/mongodb/mongo/commit/33ca45f629b898a456d2b083c435e563c886d037

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