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Type:
Task
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Resolution: Duplicate
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Priority:
Major - P3
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None
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Affects Version/s: 7.0.0-rc7
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Component/s: None
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None
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Query Optimization
The extraction of multiple top level fields can be represented in an SBE plan either as a series of getField() calls, or as a single scan over several slots.
Here is an example of the former (outputted by Bonsai):
[5] filter {shardFilter(s5, makeBsonObj(MakeObjSpec(drop, [], ["a", "b", "c"]), Nothing, s2, s3, s4))}
[4] project [s4 = getField(s1, "c")]
[3] project [s3 = getField(s1, "b")]
[2] project [s2 = getField(s1, "a")]
[1] scan s1 none none none none none none none lowPriority [] @"<collUUID>" true false
And of the latter (outputted by Stage Builders):
filter {shardFilter(s5, makeBsonObj(MakeObjSpec(drop, [], ["a", "b", "c"]), Nothing, s2, s3, s4))}
scan [s2 = a, s3 = b, s4 = c]
The latter is far more efficient, and should be the behavior of Bonsai-generated plans as part of CQF.
- duplicates
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- Closed
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- related to
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SERVER-79403 Avoid implementing stacks of EvaluationNode as stacks of SBE project operators
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- Closed
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