Template
single collection
multiple collections
mgodatagen
update
indexe
explain
Stage
Database
bson
mgodatagen
[{x:"a",t:1,s:"old"},{x:"a",t:3,s:"old"},{x:"b",t:1,s:"old"},{x:"b",t:4,s:"old"}]
Query
db.collection.update({x:"a",t:1},{$setOnInsert:{x:"a",t:1,s:"new"}},{upsert:true})
Result