[DOCS-11203] Docs for SERVER-31760: Lookup sub-pipeline is not using index for equality match Created: 12/Jan/18  Updated: 29/Oct/23  Resolved: 03/Apr/18

Status: Closed
Project: Documentation
Component/s: None
Affects Version/s: None
Fix Version/s: 3.7.1

Type: Task Priority: Major - P3
Reporter: Kay Kim (Inactive) Assignee: Kay Kim (Inactive)
Resolution: Fixed Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Documented
documents SERVER-31760 Lookup sub-pipeline is not using inde... Closed
Related
related to DOCS-12191 Document workaround for aggregation i... Closed
Participants:
Days since reply: 5 years, 45 weeks, 2 days ago
Epic Link: DOCS: 4.0 Server

 Description   

Documentation Request Summary:

The release notes list this ticket as a known issue in 3.6.0:

https://docs.mongodb.com/manual/release-notes/3.6/#known-issues-in-3-6-0

We will likely backport this fix, probably targeting 3.6.3. Do we need to do anything in the docs to reflect that the known issue has been resolved?

Engineering Ticket Description:

I am doing following aggregation to join two collection using foreign pipeline.
It seems match stage is not using index at all.

db.blogpost.aggregate([
  { $lookup: { 
    from: 'comment', 
    let: { blogpost_id: "$_id" }, 
    pipeline: [ { 
       $match: { $expr: { $eq: [ "$blogpost.id", "$$blogpost_id"] } } 
    } ], 
    as: 'comments'
  }}
])



 Comments   
Comment by Kay Kim (Inactive) [ 03/Apr/18 ]

Updated the 3.6.3 known issues list to omit this.
Since we don't mention index use and $expr anywhere else, will close as there wouldn't be any where else we would go versionchanged 4.0 for this behavior.

Comment by Githook User [ 03/Apr/18 ]

Author:

{'email': 'kay.kim@10gen.com', 'name': 'kay', 'username': 'kay-kim'}

Message: DOCS-11203: update 3.6 known issues
Branch: master
https://github.com/mongodb/docs/commit/cf421261ab54362ff44b9fbe489603d42b09dfaf

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