Mongo query keys order - mongodb

Question

Mongo query parse: sorting key based on alphabetical order is there any solution to consider based on user input?
Example :
db.user.explain().find({name: 'test user', active: true})
In the above query, mongo will parse the query to
"$and" : [
{
"active" : {
"$eq" : true
}
},
{
"name" : {
"$eq" : "test user"
}
}
]
while parsing mongo considering "active" key first and "name"
I want the query should look for "name" key first and "active" like
"$and" : [
{
"name" : {
"$eq" : "test user"
}
},
{
"active" : {
"$eq" : true
}
},
]
is there any setting/config?

Answer 1

As you have noticed parsedQuery in explain() will show you the fields in alphabetical order , but this order is not important in case there is no suitable index to be used since all documents will be loaded from the storage to memory and evaluated , so even you rename the fields to "aname" and "nactive" the execution times will be same if you dont have index , this is why it is important to create index and the order of your searched fields to coincide with the fields order in your index , for better performance in your case you may create index on:
{name:1}
or
{name:1, active:1}
But since the field "active" looks like a boolean value with very low selectivity it may not add too much difference during the search unless it is a "covered query" e.g. db.test.find({name:"Test",active:true},{name:1,_id:0})
and search happen only in memory.
Remember:
Reading from disk to memory is much more expensive then searching in memory so even your keys are intentionally renamed to satisfy the alphabetical order there will be no benefit if you dont create index and the mongod process perform COLLSCAN on the full collection.