You need to capture last update time yourself. For my application, I keep an AuditTrail object, which captures AuditEvents. These events occur on any insert, update, or delete of an object (delete is virtual in my system, just setting a flag). For each AuditEvent, I keep track of the date, authenticated user, db action, and … Read more
Using bulk operations Bulk operations might be of help here. An unordered bulk.find(queryDoc).remove() basically is a version of db.collection.remove(queryDoc) optimized for large numbers of operations. It’s usage is pretty straightforward: var bulk = db.yourCollection.initializeUnorderedBulkOp() bulk.find(yourQuery).remove() bulk.execute() Please see Bulk.find().remove() in the MongoDB docs for details. The idea behind this approach is not to speed up … Read more
As the docs you quote indicate, you can’t use $lookup on a sharded collection. So the best practice workaround is to perform the lookup yourself in a separate query. Perform your aggregate query. Pull the “localField” values from your query results into an array, possibly using Array#map. Perform a find query against the “from” collection, … Read more
You can use any type of value for an _id field (except for Arrays). If you choose not to use ObjectId, you’ll have to somehow guarantee uniqueness of values (casting ObjectId to string will do). If you try to insert duplicate key, error will occur and you’ll have to deal with it. I’m not sure … Read more
What you need is the $cond operator of aggregation framework. One way to get what you want would be: db.foo.aggregate([ { $project: { item: 1, lessThan10: { // Set to 1 if value < 10 $cond: [ { $lt: [“$value”, 10 ] }, 1, 0] }, moreThan10: { // Set to 1 if value > … Read more
Check mongodb logs. In my case mongodb could not find directory from mongod.cfg
You should use regexp for this, i.e. { “Category” : /^BOND.*/ } for categories begins with BOND, or { “Category” : /.*BOND.*/ } for categories contains BOND within
.update(Authors:{$elemMatch:{Slug:”slug”}}, {$set: {‘Authors.$.Name’:”zzz”}});
I’ve created a simple health check for mongodb, it uses the mongo client to send a simple query request (eg. db.stats()) to the server. $ mongo 192.168.5.51:30000/test MongoDB shell version: 3.2.3 connecting to: 192.168.5.51:30000/test mongos> db.stats() { “raw” : { “set1/192.168.5.52:27000,192.168.5.53:27000” : { “db” : “test”, “collections” : 8, “objects” : 50, “avgObjSize” : 73.12, … Read more
The idea behind MongoDB is to eliminate (or at least minimize) relational data. Have you considered just embedding the attendance data directly into each student record? This is actually the preferred design pattern for MongoDB and can result in much better performance and scalability. If you truly need highly relational and normalized data, you might … Read more