Details
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Improvement
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Resolution: Fixed
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Major - P3
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None
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None
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None
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Fully Compatible
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QO 2021-09-06, QO 2021-09-20, QO 2021-10-04
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135
Description
Currently when run on a shard server, a $lookup will target shards to attach a cursor source regardless of whether the 'from' collection is sharded or unsharded. This is because, if the source collection is sharded and the 'from' collection is unsharded, the $lookup could be running on a non-primary shard and must target the primary (where the 'from' collection lives) to get correct results. However, if the $lookup is running on the primary shard of the database and the 'from' collection is unsharded, it is safe to perform local reads instead of targeting shards.
Attachments
Issue Links
- depends on
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SERVER-58727 Perform local operation when AsyncRequestsSender only targets local shard
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- Closed
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