At the current state, ExportCollection() loads all documents in memory before exporting them to a json file.

	result, err := db.FindAll(query.NewQuery(collectionName))
	if err != nil {
		return err
	}

	docs := make([]map[string]interface{}, 0)
	for _, doc := range result {
		docs = append(docs, doc.AsMap())
	}

	jsonString, err := json.Marshal(docs)
	if err != nil {
		return err
	}

This is far from being optimized, since collections could contain thousands or millions of documents.
Export should thus performed gradually by writing documents to the output file one by one (the ForEach() method can be used to iterate no documents).