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Type: Improvement
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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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None
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Fully Compatible
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Query 2017-08-21, Query 2017-09-11
Currently, when a sharded pipeline is explained, we expose a boolean field needsPrimaryShardMerger to indicate whether the merge part of the pipeline must be run on the database's primary shard. Given that SERVER-22760 will make it possible for mongoS to merge directly from the shards, this explain format should be updated to provide more detailed information.
Some possible approaches include:
- A string field mergerType which simply takes the value of mongos or mongod
- A more detailed merger field identifying the shard or mongos which is to perform the merge. Note that in the case of a shard merge, this information may not be available at explain time.
- is related to
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SERVER-22760 Sharded aggregation pipelines which involve taking a simple union should merge on mongos
- Closed