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Type: Improvement
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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: None
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Component/s: None
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None
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Query Execution
In SBE projections are isolated but there are cases where there are many projections sharing the same prefix e.g:
$project: { "d" : "a.b.c.d", "e" : "a.b.c.e", "f" : "a.b.c.f", "g" : "a.b.c.g", "h" : "a.b.c.h", }
In the above example all the work to navigate up until c is repeated and thrown away on every projected field.
See the attached flame graph, query and explain plan for a real life example derived from HELP-47436
- duplicates
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SERVER-79548 [SBE] optimize pulling multiple fields out of a large document
- Open