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Type:
Improvement
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Resolution: Done
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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 2018-01-29, Query 2018-02-12, Query 2018-02-26, Query 2018-03-12
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(copied to CRM)
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0
In the case of an aggregation framework query the first batch of results asked from the mergerPart to the shards are done asynchronously, however when it needs to get a second batch to fullfill the query it is virtually mono-threaded as the call to getNext is synchronous.
I think it would be good to be able to overcome this limitation and make all subsequent fetches to be done in the background.
You can see here (https://github.com/ahom/jupyter-notebooks/blob/master/mongo_cs32044/notebook.ipynb) a representation of this behavior.
On the Y axis are the shards, on the X axis is the time. Starting from second batch seems is completely synchronous.
Cheers,
Antoine
- depends on
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SERVER-33660 Once getMores include lsid, sharded aggregations with $mergeCursors can hang
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- Closed
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SERVER-32307 Make AsyncResultsMerger kill sequence issue killCursors without waiting for outstanding batches
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- Closed
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- is depended on by
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- Closed
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- Closed
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- is duplicated by
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- Closed
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- related to
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- Closed
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