Context

• config.chunks collections with 811k documents
• Compass Version 1.21.2

Steps:

1. Add $group stage with code: 

    {
    _id: "$shard",
    count: {
    $sum: 1
    }
   }

2. Turn off sample mode
3. Add a $out stage to collection chunks_summary
4. See that output document in chunks_summary includes { "_id" : "shard_5", "count" : 5 }

Expected:

• The document in chunks_summary should have had count 626.
• I would never expect the sampling to be applied to the $out even if Sample mode was enabled

Theory

• It seems that turning off sample mode on an existing pipeline doesn't apply directly.

Workaround:

• If I start a new pipeline, then turn off sample mode before creating any stages it works.