[DOCS-13209] Agg pipeline + sharding behavior different in 2 places Created: 07/Nov/19  Updated: 30/Oct/23  Resolved: 25/Sep/20

Status: Closed
Project: Documentation
Component/s: manual
Affects Version/s: None
Fix Version/s: Server_Docs_20231030

Type: Bug Priority: Major - P3
Reporter: Sheeri Cabral (Inactive) Assignee: Dave Cuthbert (Inactive)
Resolution: Fixed Votes: 0
Labels: docs-sharding
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Participants:
Days since reply: 3 years, 19 weeks, 5 days ago
Epic Link: DOCSP-1769

 Description   

Description

The docs for "Aggregation Pipeline and Sharded Collections" https://docs.mongodb.com/manual/core/aggregation-pipeline-sharded-collections/ has a behavior section that says

"For aggregation operations that must run on multiple shards, if the operations do not require running on the database’s primary shard, these operations will route the results to a random shard to merge the results to avoid overloading the primary shard for that database. The $out stage and the $lookup stage require running on the database’s primary shard."  (starting 3.2)

 

But the docs for mongos https://docs.mongodb.com/manual/core/sharded-cluster-query-router/#routing-and-results-process say

"Changed in version 3.6: For aggregation operations that run on multiple shards, if the operations do not require running on the database’s primary shard, these operations may route the results back to the mongos where the results are then merged."

I have confirmed with the query team that the latter behavior is correct and the first doc with the notes on the 3.2 behavior should be overwritten or caveat-ed.

Scope of changes

Impact to Other Docs

MVP (Work and Date)

Resources (Scope or Design Docs, Invision, etc.)



 Comments   
Comment by Githook User [ 25/Sep/20 ]

Author:

{'name': 'Dave Cuthbert', 'email': 'dave.cuthbert@mongodb.com', 'username': 'davemungo'}

Message: DOCS-13209 update conflicting doc with newer behavior
Branch: v3.6
https://github.com/mongodb/docs/commit/b54fcaad8c575061c6a2e55492732c5225923a32

Comment by Githook User [ 25/Sep/20 ]

Author:

{'name': 'Dave Cuthbert', 'email': 'dave.cuthbert@mongodb.com', 'username': 'davemungo'}

Message: DOCS-13209 update conflicting doc with newer behavior
Branch: v4.0
https://github.com/mongodb/docs/commit/83903f77660e9eff406bffe32cc705356537dabd

Comment by Githook User [ 25/Sep/20 ]

Author:

{'name': 'Dave Cuthbert', 'email': 'dave.cuthbert@mongodb.com', 'username': 'davemungo'}

Message: DOCS-13209 update conflicting doc with newer behavior
Branch: v4.2
https://github.com/mongodb/docs/commit/9cdf32dbc568e7e2ddb62b07fa65f46f9bef851e

Comment by Githook User [ 23/Sep/20 ]

Author:

{'name': 'Dave Cuthbert', 'email': 'dave.cuthbert@mongodb.com', 'username': 'davemungo'}

Message: DOCS-13209 update conflicting doc with newer behavior
Branch: master
https://github.com/mongodb/docs/commit/32dc30a14cf00fbbd9f0ae6614668cbea85c48be

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