Sort by best matches mongodb - mongodb

Question

I have collection of data in Mongodb, i want to give best matches suggestion while user input query in our suggestion box,
when user start typing com suggestion should be:
Computer
Computer Science
something more alike
I am sorting in Node by getting all matched data from mongo first and then give a rank to each data
function rank(name, q) {
var len = name.length,
lastIndex = -1;
for(var i = 0; i < q.length; i++) {
var n = name.indexOf(q[i], (lastIndex + 1));
if(n !== -1) {
len--;
lastIndex = n;
}
}
return len;
}
var query = 'com';
// giving rank to data
data = data.map(function(v) {
v.rank = rank(v.value, query);
return v;
});
// sorting by rank
data = data.sort(function(a, b) {
return a.rank - b.rank
});
It is giving me satisfied result, but it will be too slow while dealing with large data.
I want let mongodb engine to deal with sorting and give me just limited best matches result.

Answer 1

Maybe you could do it through mapreduce. Map-reduce is a data processing paradigm for condensing large volumes of data into useful aggregated results.
var mapFn = function(){
var len = this.name.length,
lastIndex = -1;
var q = 'com';
for(var i = 0; i < q.length; i++) {
var n = this.name.indexOf(q[i], (lastIndex + 1));
if(n !== -1) {
len--;
lastIndex = n;
}
}
emit(len, this);
};
var reduceFn = function(key, values){
return values.sort(function(a,b){
return a.name - b.name;
});
};
db.collection.mapReduce(mapFn, reduceFn, { out: { reduce: 'result_collection'}});