This answer is obsolete : the dropDups option was removed in MongoDB 3.0, so a different approach will be required in most cases. For example, you could use aggregation as suggested on: MongoDB duplicate documents even after adding unique key. If you are certain that the source_references.key identifies duplicate records, you can ensure a unique index … Read more
You should use find, like you already are, and not aggregation which will be slower since it needs to scan all the values of _id fields to figure out the max. As comments pointed out there is no difference between using find() and findOne() – functionally or elegance-wise. In fact, findOne in the shell (and … Read more
In Mongo 2.8 RC2 there is a new data aggregation operator: $dateToString which can be used to group by a day and simply have a “YYYY-MM-DD” in the result: Example from the documentation: db.sales.aggregate( [ { $project: { yearMonthDay: { $dateToString: { format: “%Y-%m-%d”, date: “$date” } }, time: { $dateToString: { format: “%H:%M:%S:%L”, date: … Read more
To get the URL for your deployed site at meteor.com use the command (you may need to provide your site password if you password protected it): meteor mongo –url YOURSITE.meteor.com Which will return something like : mongodb://client:[email protected]:27017/YOURSITE_meteor_com Which you can give to a program like mongodump mongodump -u client -h sky.member1.mongolayer.com:27017 -d YOURSITE_meteor_com\ -p PASSWORD … Read more
On my ubuntu server, just run: sudo rm /var/lib/mongodb/mongod.lock mongod –repair sudo service mongodb start
The main purpose of the aggregation framework is to ease the query of a big number of entries and generate a low number of results that hold value to you. As you have said, you can also use multiple find queries, but remember that you can not create new fields with find queries. On the … Read more
I am not sure if this will help your situation (that is if it stills exists), however, after scouring the web for a similar issue. I was creating a native query from a persistence EntityManager to perform an update. Query query = entityManager.createNativeQuery(queryString); I was receiving the following error: caused by: javax.persistence.TransactionRequiredException: Executing an update/delete … Read more
Mongo includes a mongoexport utility (see docs) which can dump a collection. This utility uses the native libmongoclient and is likely the fastest method. mongoexport -d <database> -c <collection_name> Also helpful: -o: write the output to file, otherwise standard output is used (docs) –jsonArray: generates a valid json document, instead of one json object per … Read more
I would say, it depends on kind of dev team you are and your application needs. For example, if you require a lot of querying, that mostly means it would be more work for your developers to use Redis, where your data might be stored in variety of specialized data structures, customized for each type … Read more
You can do… JavaScript (shell): db.getCollectionNames() Node.js: db.listCollections() Non-JavaScript (shell only): show collections The reason I call that non-JavaScript is because: $ mongo prodmongo/app –eval “show collections” MongoDB shell version: 3.2.10 connecting to: prodmongo/app 2016-10-26T19:34:34.886-0400 E QUERY [thread1] SyntaxError: missing ; before statement @(shell eval):1:5 $ mongo prodmongo/app –eval “db.getCollectionNames()” MongoDB shell version: 3.2.10 connecting … Read more