I am trying to query MongoDB to obtain something like:
"get persons with age not in the range [30,40]"
I am doing:
db.persons.find({'age' : {$nin : [{$lt : 30},{$gt : 40}]}})
which is not working for me. I know that I could do something like people with age<30 AND people with age>40 but I was wondering if I can use the "not in" operator... thanks
What about using the OR conjunction like this:
db.persons.find($or: [{'age': {$lt: 30}},{'age': {$gt : 40}}])
$in / $nin are operators used for querying for discrete values in a list and can not be used for range searches.
In your example, the query with $nin would have to be
db.persons.find({age:{$nin:[30,31,32,33,34,35,36,37,38,39,40]}})
which is not at all practical and, furthermore, would not make use of an index:
db.persons.ensureIndex({age:1})
db.persons.find({age:{$nin:[30,31,32,33,34,35,36,37,38,39,40]}}).explain()
{
"cursor" : "BasicCursor",
"isMultiKey" : false,
"n" : 1,
"nscannedObjects" : 1,
"nscanned" : 1,
"nscannedObjectsAllPlans" : 1,
"nscannedAllPlans" : 1,
"scanAndOrder" : false,
"indexOnly" : false,
"nYields" : 0,
"nChunkSkips" : 0,
"millis" : 0,
"indexBounds" : {
},
"server" : "Aspire-5750:27017"
}
Sgoettschkes' answer above is correct and would use the index:
db.persons.find({$or: [{'age': {$lt: 30}},{'age': {$gt : 40}}]}).explain()
{
"clauses" : [
{
"cursor" : "BtreeCursor age_1",
"isMultiKey" : false,
"n" : 0,
"nscannedObjects" : 0,
"nscanned" : 0,
"nscannedObjectsAllPlans" : 0,
"nscannedAllPlans" : 0,
"scanAndOrder" : false,
"indexOnly" : false,
"nYields" : 0,
"nChunkSkips" : 0,
"millis" : 12,
"indexBounds" : {
"age" : [
[
-1.7976931348623157e+308,
30
]
]
}
},
{
"cursor" : "BtreeCursor age_1",
"isMultiKey" : false,
"n" : 1,
"nscannedObjects" : 1,
"nscanned" : 1,
"nscannedObjectsAllPlans" : 1,
"nscannedAllPlans" : 1,
"scanAndOrder" : false,
"indexOnly" : false,
"nYields" : 0,
"nChunkSkips" : 0,
"millis" : 0,
"indexBounds" : {
"age" : [
[
40,
1.7976931348623157e+308
]
]
}
}
],
"n" : 1,
"nscannedObjects" : 1,
"nscanned" : 1,
"nscannedObjectsAllPlans" : 1,
"nscannedAllPlans" : 1,
"millis" : 12,
"server" : "Aspire-5750:27017"
}
For more information on querying effectively, see http://docs.mongodb.org/manual/core/read-operations/
