mongodb how to mongodump only indexes to another mongodb instance

Question

I have a mongodb instance with a lot of data, now I need to start up a new instance with the same structure without data.

how to get it done?

Answer 1

You can do that with the "query" option, with a query that does not return any document. Something like:

mongodump -q '{ "foo" : "bar"  }'

This will dump all the dbs and indexes, you can then do a mongorestore to recreate them into another mongod instance

See documentation: http://docs.mongodb.org/manual/reference/program/mongodump/#cmdoption--query

Answer 2

You can login into mongo shell and execute the following code statements to generate creating indexes statements. After that, use the statements to recreate indexes.

var collectionList = db.getCollectionNames();
for(var index in collectionList){
    var collection = collectionList[index];
        var cur = db.getCollection(collection).getIndexes();
        if(cur.length == 1){
            continue;
        }
        for(var index1 in cur){
            var next = cur[index1];
            if(next["name"] == '_id_'){
                continue;
            }
       var unique=next["unique"]?true:false;
       print("try{ db.getCollection(\""+collection+"\").createIndex("+JSON.stringify(next["key"])+",{unique:"+unique+"},{background:1})}catch(e){print(e)}");}}