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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: Aggregation Framework
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Labels:None
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Fully Compatible
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Query 12 (04/04/16), Query 13 (04/22/16)
When a $match contains an $in array with a single exact shard key match, the aggregation is not targetted to a single shard.
The listed repro produces the following output on 3.0.10:
$ mongo aggregation.js
MongoDB shell version: 3.0.10
connecting to: test
{ "e1" : null }
{
"e2" : {
"shardsPart" : [
{
"$match" : {
"a" : {
"$in" : [
1
]
}
}
}
],
"mergerPart" : [ ]
}
}
And the following output on 3.2.4:
$ mongo aggregation.js
MongoDB shell version: 3.2.4
connecting to: test
{ "e1" : null }
{
"e2" : {
"shardsPart" : [
{
"$match" : {
"a" : {
"$in" : [
1
]
}
}
}
],
"mergerPart" : [ ]
}
}
Notes:
- a find with / without the $in is correctly targetted to a single shard.
- I haven't tested multiple $in all targetted but it is likely that will also invoke a merge
- this issue is unrelated to
SERVER-18940as it is an exact shard key match. - This issue is an related but distinct from
SERVER-7656.
- duplicates
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SERVER-18940 Optimise sharded aggregations that are targeted to a single shard
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- Closed
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-
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- Closed
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- is related to
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- Closed
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