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Type:
Bug
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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: 3.1.8
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Component/s: Aggregation Framework
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None
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Fully Compatible
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ALL
I have a collection of two thousand documents where each document is either just _id or _id and integer field "a" (different values).
> db.noindex.aggregate({$sample:{size:2}})
{ "_id" : ObjectId("558479e1acb64a95da32c877"), "a" : 182 }
{ "_id" : ObjectId("558479b5acb64a95da32c3d9") }
> db.noindex.aggregate({$sample:{size:2}})
{ "_id" : ObjectId("558479b5acb64a95da32c3d9") }
{ "_id" : ObjectId("558479e1acb64a95da32c877"), "a" : 182 }
> db.noindex.aggregate({$sample:{size:2}})
{ "_id" : ObjectId("558479b5acb64a95da32c3d9") }
{ "_id" : ObjectId("558479e1acb64a95da32c877"), "a" : 182 }
db.noindex.aggregate({$sample:{size:3}})
assert: command failed: {
"ok" : 0,
"errmsg" : "$sample stage could not find a non-duplicate document after 100 while using a random cursor. This is likely a sporadic failure, please try again.",
"code" : 28799
} : aggregate failed
_getErrorWithCode@src/mongo/shell/utils.js:23:13
doassert@src/mongo/shell/assert.js:13:14
assert.commandWorked@src/mongo/shell/assert.js:259:5
DBCollection.prototype.aggregate@src/mongo/shell/collection.js:1211:5
@(shell):1:1
2015-09-18T15:48:35.893-0400 E QUERY [thread1] Error: command failed: {
"ok" : 0,
"errmsg" : "$sample stage could not find a non-duplicate document after 100 while using a random cursor. This is likely a sporadic failure, please try again.",
"code" : 28799
} : aggregate failed :
_getErrorWithCode@src/mongo/shell/utils.js:23:13
doassert@src/mongo/shell/assert.js:13:14
assert.commandWorked@src/mongo/shell/assert.js:259:5
DBCollection.prototype.aggregate@src/mongo/shell/collection.js:1211:5
@(shell):1:1
This suggests it's somehow determining duplicate incorrectly or else some other check is wrong...
Note also that sample being run multiple times always returns the same two records, which may be related...
- duplicates
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- Closed
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