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Type:
Bug
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Resolution: Done
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Priority:
Major - P3
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None
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Affects Version/s: 2.0.1
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Component/s: Index Maintenance
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None
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ALL
This is related to http://groups.google.com/group/mongodb-user/browse_thread/thread/9f08de0b3c3e1a13
Explain shows correct bounds for a query on an array of documents if the array only includes one document:
PRIMARY> db.foo.ensureIndex({'aH.s': 1, 'aH.m': 1, 'aH.u': 1})
PRIMARY> db.foo.insert({aH: [{s: 'a', m: 'b', u: 'c'}]})
PRIMARY> db.foo.find({'aH.s': 'x', 'aH.m': 'y', 'aH.u': 'z'}).explain()
{
"cursor" : "BtreeCursor aH.s_1_aH.m_1_aH.u_1",
"nscanned" : 0,
"nscannedObjects" : 0,
"n" : 0,
"millis" : 0,
"nYields" : 0,
"nChunkSkips" : 0,
"isMultiKey" : false,
"indexOnly" : false,
"indexBounds" : {
"aH.s" : [
[
"x",
"x"
]
],
"aH.m" : [
[
"y",
"y"
]
],
"aH.u" : [
[
"z",
"z"
]
]
}
}
If you then insert another document that has more than one document in the array the bounds listed by explain seem wrong:
PRIMARY> db.foo.insert({aH: [{s: 'd', m: 'e', u: 'f'}, {s: 'g', m: 'h', u: 'i'}]})
PRIMARY> db.foo.find({'aH.s': 'x', 'aH.m': 'y', 'aH.u': 'z'}).explain()
{
"cursor" : "BtreeCursor aH.s_1_aH.m_1_aH.u_1",
"nscanned" : 0,
"nscannedObjects" : 0,
"n" : 0,
"millis" : 0,
"nYields" : 0,
"nChunkSkips" : 0,
"isMultiKey" : true,
"indexOnly" : false,
"indexBounds" : {
"aH.s" : [
[
"x",
"x"
]
],
"aH.m" : [
[
{
"$minElement" : 1
},
{
"$maxElement" : 1
}
]
],
"aH.u" : [
[
{
"$minElement" : 1
},
{
"$maxElement" : 1
}
]
]
}
}