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    Type:New Feature 
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    Resolution: Fixed
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    Priority:Major - P3 
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    Affects Version/s: None
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    Component/s: Aggregation Framework
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    None
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        Fully Compatible
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        Query 2020-01-27, Query 2020-02-10, Query 2020-02-24
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        None
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        None
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        None
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        None
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It looks like there will be some C++ changes necessary to get this to work, along with some testing to confirm. I've attached a POC patch which is based of the one attached to SERVER-45452. It works, but has a strange use of expCtx->isParsingViewDefinition` which we should look into ways of avoiding.
- depends on
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                    SERVER-45452 [no sharding] Support and test reading from a view using $unionWith -         
- Closed
 
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- is depended on by
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                    SERVER-45563 Support reading from a view on a sharded collection using $unionWith -         
- Closed
 
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