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Type:
Bug
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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: None
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None
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Query Optimization
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Fully Compatible
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ALL
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v8.0
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QO 2024-04-01
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54
https://jira.mongodb.org/browse/BF-32195 was caused by a partial unique index that includes this filter in an OR
"$and" : [ { "obj.obj.obj.obj.obj.obj.num" : { "$type" : "long" } } ]
This query results in differing unique index behavior on the two versions.
db.fuzzer.runCommand({ "update" : "fuzzer", "updates" : [ { "q" : { }, "u" : [ { "$addFields" : { "obj.obj.obj.obj.obj.obj.num" : { "$mod" : [ NumberLong("314159265358979383"), 34928 ] } } } ], "multi" : true } ]})
The $mod on 7.0 produces a long (and so send every document in the collection to the index, resulting in a duplicate key error). On 7.3 / 8.0 it produces an int and does not result in a duplicate key error.
https://jira.mongodb.org/browse/DEVPROD-5208 resolved a similar issue.
Avoiding "$type" : "long" anywhere in a partial unique index's filter should resolve the issue.