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Type:
Task
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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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Labels:
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Minor Change
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Query 2018-09-24
In MongoDB 4.0 and earlier, we explicitly ban readConcern level "majority" for aggregation pipelines containing $out.
auto readConcernLevel = repl::ReadConcernArgs::get(expCtx->opCtx).getLevel();
uassert(ErrorCodes::InvalidOptions,
"$out cannot be used with a 'majority' read concern level",
readConcernLevel != repl::ReadConcernLevel::kMajorityReadConcern);
However, it does allow readConcern level "linearizable". As linearizability is a property of a single document, we will ban a $out aggregation with readConcern level "linearizable", as it isn't clear what semantics will be offered to our users.
This is a backwards-breaking change in 4.2; however, we will allow support for readConcern level "majority" in $out pipelines in SERVER-20445.
- is documented by
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- Closed
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- is related to
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SERVER-20445 Add support for majority read concern level to Aggregation $out
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- Closed
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