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Type:
Task
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Status: Open
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Priority:
Major - P3
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Resolution: Unresolved
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Affects Version/s: None
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Labels:None
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# Replies:0
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Last comment by Customer:true
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Epic Link:
Description
Downstream Change Summary
We added a new expression, $sampleRate, which lets you select a desired fraction or percentage of documents. (Contrast with $sample, which lets you select a desired number of documents.)
Description of Linked Ticket
This match expression takes a floating point number between 0 and 1 (both inclusive) with 0 matching nothing and 1 matching all. It desugars to {$expr: {$rand: ...}}
Unlike $sample, which is an experession, $sampleRate is a match-expression, which can go inside .find() or {$match: _}.
For example, the pipeline:
{$match: {$sampleRate: 0.25}}
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Would select on average 1/4 of the input documents. It could desugar to
{$match: {$expr: {$lt: [ {$rand: {}}, 0.25 ]}}}
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Scope of changes
Impact to Other Docs
MVP (Work and Date)
Resources (Scope or Design Docs, Invision, etc.)
- documents
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SERVER-48474 Add $sampleRate match expression
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- Closed
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