[DOCS-15336] Investigate changes in SERVER-65960: Fall back to classic engine when NLJ is chosen and disable SBE on the right of classic $lookup Created: 12/May/22  Updated: 13/Nov/23  Resolved: 10/Feb/23

Status: Closed
Project: Documentation
Component/s: manual, Server
Affects Version/s: None
Fix Version/s: 6.1.0-rc0, 6.0.0-rc9, Server_Docs_20231030, Server_Docs_20231106, Server_Docs_20231105, Server_Docs_20231113

Type: Task Priority: Major - P3
Reporter: Backlog - Core Eng Program Management Team Assignee: Alison Huh
Resolution: Won't Do Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Documented
documents SERVER-65960 Fall back to classic engine when NLJ... Closed
Participants:
Days since reply: 51 weeks, 5 days ago
Epic Link: DOCSP-22649

 Description   
Original Downstream Change Summary

If we land this patch, NLJ will no longer be pushed down to SBE.
This is when no index can be used on the foreign side and the foreign side is too big to use a hash join.

Description of Linked Ticket

This task should check the index catalog for a wildcard, sparse, partial (possibly other special) indexes against the foreign collection that cover the join field, and if such an index exists we need to fall-back to the classic engine. 

The main reason is these special indexes aren't supported by sbe currently, and we would replace an ix_scan with a collscan and incur a perf hit.



 Comments   
Comment by Alison Huh [ 10/Feb/23 ]

No changes to customer/user experience. SERVER ticket marked as downstream not needed.

Comment by Education Bot [ 06/Jun/22 ]

Fix Version updated for upstream SERVER-65960:
6.1.0-rc0, 6.0.0-rc9

Comment by Education Bot [ 06/Jun/22 ]

Fix Version updated for upstream SERVER-65960:
6.0.0-rc9

Comment by Education Bot [ 25/May/22 ]

Fix Version updated for upstream SERVER-65960:
6.0 Required

Comment by Education Bot [ 12/May/22 ]

Fix Version updated for upstream SERVER-65960:

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