Details
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Bug
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Resolution: Done
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Trivial - P5
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None
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None
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None
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Query
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ALL
Description
The 2.7 nightly has a change (regression?) from 2.6 running parallelCollectionScan on an empty collection. In 2.6, it still returned a cursor. Somewhere in 2.7, it changed to returning no cursors at all. This may break drivers that expect at least one cursor to be returned.
Under 2.6:
> use test
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switched to db test
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> db.test_coll.insert({})
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WriteResult({ "nInserted" : 1 })
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> db.test_coll.remove({})
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WriteResult({ "nRemoved" : 1 })
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> db.test_coll.find({})
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> db.runCommand({parallelCollectionScan:"test_coll", numCursors:3})
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{
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"cursors" : [
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{
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"cursor" : {
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"firstBatch" : [ ],
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"ns" : "test.test_coll",
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"id" : NumberLong("64941895831323")
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},
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"ok" : true
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}
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],
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"ok" : 1
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}
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Under 2.7 (4f01ffd9cbbb0dcb4ee2f9167ad2337178259ba9-2014-07-23):
> use test
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switched to db test
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> db.runCommand(
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Display all 182 possibilities? (y or n)
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> db.test_coll.insert({})
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WriteResult({ "nInserted" : 1 })
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> db.test_coll.remove({})
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WriteResult({ "nRemoved" : 1 })
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> db.test_coll.find({})
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> db.runCommand({parallelCollectionScan:"test_coll", numCursors:3})
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{ "cursors" : [ ], "ok" : 1 }
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