[SERVER-50299] Shard Targeting for $in statements Created: 22/Jun/20  Updated: 27/Aug/20  Resolved: 27/Aug/20

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

Type: Improvement Priority: Major - P3
Reporter: Dawid Esterhuizen Assignee: Max Hirschhorn
Resolution: Duplicate Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Duplicate
duplicates SERVER-1007 rewrite $in queries on shard key to o... Backlog
Related
related to SERVER-4960 Optimize shard selection on $in queries Backlog
Participants:

 Description   

HI 

Working with a Client we were exploring ways to mitigate load issues on the mongod hosts on a Sharded cluster. 

The particular client is doing multiple $in statements in each query but have large lists for up to 1000 entries per $in part.  Based on testing on both Our and the client side we were able to see significant advantages of trying to target each $in's entries to a single shard. Thus avoiding scatter gather queries foe each fo the $in queries.

The optimisation could be both on the mongos or on the driver side, and on the dirver and could make it invisible to the client.



 Comments   
Comment by Garaudy Etienne [ 13/Aug/20 ]

What exactly does "mitigate load issues" mean here?

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