Is there a way to query for objects with not same values on some field? For example I have Records:
{ id : 1, name : "my_name", salary : 1200 }
{ id : 2, name : "my_name", salary : 800 }
{ id : 3, name : "john", salary : 500 }
Query : find all with NOT_THE_SAME(name)
I just want records with id 1 and 3 because I specified that I don't want records with same value in field name or 2 and 3, it does not matter in this situation.
If you don't care about the content of varying fields but want the whole records, this will keep the (whole, thanks to $$ROOT) first document found for each "name" :
db.coll.aggregate([
{ "$group": {
"_id": "$name",
"doc": { "$first": "$$ROOT" }
}},
{ "$replaceRoot": {
"newRoot": "$doc"
}}
])
$replaceRoot will serve them as documents instead of encapsulating them in a doc field with _id.
If you are concerned about the content of the varying fields, I guess you may want to sort the documents first :
db.coll.aggregate([
{ "$sort": { "$salary": 1 }},
{ "$group": {
"_id": "$name",
"doc": { "$first": "$$ROOT" }
}},
{ "$replaceRoot": {
"newRoot": "$doc"
}}
])
db.test.distinct("name")
db.test.aggregate([{$group: {_id: "$name", salary: {$max: "$salary"}}}])