[SERVER-60885] Loading Simple8b block starting with RLE is not initialized with correct previous value Created: 21/Oct/21  Updated: 29/Oct/23  Resolved: 22/Oct/21

Status: Closed
Project: Core Server
Component/s: None
Affects Version/s: None
Fix Version/s: 5.2.0

Type: Bug Priority: Major - P3
Reporter: Henrik Edin Assignee: Henrik Edin
Resolution: Fixed Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Backwards Compatibility: Fully Compatible
Operating System: ALL
Sprint: Execution Team 2021-11-01
Participants:

 Description   

When building a stream of Simple8b blocks the encoder acts as if they are a long continuous stream.
However, after every 16 blocks we write a control block. When a reader encounters the control block it re-initializes the decoders and default initialize the previous value to 0.
If the first Simple8b block after the control code is an RLE block it will then use 0 as the previous instead of the correct value.

To reproduce this you need a monotonically increasing value (like a counter) where we can get a RLE block for a value different than 0.



 Comments   
Comment by Githook User [ 21/Oct/21 ]

Author:

{'name': 'Henrik Edin', 'email': 'henrik.edin@mongodb.com', 'username': 'henrikedin'}

Message: SERVER-60885 Initialize Simple8b block with last value from previous Simple8b block

Needed in case the next Simple8b block starts with RLE
Branch: master
https://github.com/mongodb/mongo/commit/06ec9120353ae89d1821fd01d9bd3b3c5345509c

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