Search any value in MongoDB using regular expressions?

Question

I'm very new to MongoDB and regex so please bear with me. The MongoDB documentation has an example for searching with regular expressions:

http://docs.mongodb.org/manual/reference/operators/#_S_regex

However, it only shows how to search the values of predetermined keys. I'm unsure how to write a query to search all values in a collection, if anyone can point it out that would be great.

Answer 1

If you didn't care about size of DB (or performance), you could potentially use a mapReduce function to de-normalize the data into a structure which is more easily searched. But, this will significantly increase the size of the DB as you'll duplicate all data for the collection.

Pseudo-code:

// recursive
// building a full property path
for(var key in obj) {
    emit(this._id, { orig: obj[key], src: path + "." + key });
    // recursive call emitChildren(path, key)
}

Depending on the complexity of the data, it could be reasonable.

Or, you might be able to use $where to do a regex on each key/value of all documents (as you can execute arbitrary JavaScript when using $where).

No option is going to perform well (even a built in option) nor play to the strengths of mongoDB if you're running a regular expression on every value in every document in a collection.