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Type:
Task
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Resolution: Done
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Priority:
Major - P3
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None
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Affects Version/s: None
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Component/s: None
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Labels:
Engineering Ticket Description:
I was looking at the optimizing aggregation pipelines docs page and didn't see this one listed.
This is only possible if the subsequent $match doesn't use any computed fields, but there could be a large win with regards to index usage if you could move the $match prior to a $project.
For example:
{ $project: { a: 1, b: 1, newField: { $add: ["$a", "$b"] } } },
{ $match: { a : { $gt: 10 } }
is the same as
{ $match: { a : { $gt: 10 } },
{ $project: { a: 1, b: 1, newField: { $add: ["$a", "$b"] } } }
because the $match is only using fields that exist in the original document.
- documents
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SERVER-19153 Conditionally push $match before $project
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- Closed
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- is related to
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- Closed
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- related to
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- Closed
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