After running some queries, I came to the conclusion that $in doesn’t work for an array of arrays. You can use $elemMatch instead and it’ll work, but it is frustrating that MongoDB’s documentation doesn’t warn about it. I created this document: { “_id”: “51cb12857124a215940cf2d4”, “level1”: [ [ “item00”, “item01” ], [ “item10”, “item11” ] ], … Read more
Well… There appears to be a version conflict: you are probably running a 32bit version of Mongo. Just do as they say and actually use the other default storage engine: Write the command as follows in your Mongo/bin directory: mongod –storageEngine=mmapv1 –dbpath [your-path] Should solve the problem. I guess you don’t quite mind about using … Read more
Since this is a text search query we are talking about then the most optimal form is this: db.collection.aggregate([ { “$match”: { “$text”: { “$search”: “cake tea” } } }, { “$sort”: { “score”: { “$meta”: “textScore” } } }, { “$limit”: skip + limit }, { “$skip”: skip } ]) The rationale on the … Read more
A couple tips: Try running the same query from mongodb at the command line, see if you get any results. Is the “campaign_id” defined as an ObjectId in your schema? If so, try searching using the ObjectId type. For example: var ObjectId = require(‘mongoose’).Types.ObjectId; var query = { campaign_id: new ObjectId(campaign._id) };
I expect it’s just a typo in the documentation. The _id field is primary key for every document. It’s called _id and is also accessible via id. Attempting to use an id key may result in a illegal ObjectId format error. That section is just indicating that the automatically generated ObjectIDs start with a timestamp … Read more
I suggest you to use 2 queries: db.collection.count() will return total number of items. This value is stored somewhere in Mongo and it is not calculated. db.collection.find().skip(20).limit(10) here I assume you could use a sort by some field, so do not forget to add an index on this field. This query will be fast too. … Read more
There is a few rules that will help here to get good and valuable answer for MongoDB related question. Please see below some common categories and steps that will help with gathering data which could help you to find a good answer faster. Please attach all documents in text format as screenshot cannot be pasted … Read more
As you would be aware by now, $slice is only used in projection to limit the array elements returned in the results. So you would be stuck with processing the list programmatically with results from a find(). A better approach is to use aggregate. But first let’s consider how $slice is used: > db.collection.find({},{ relevancy: … Read more
Indexes in MongoDB are stored in a B-tree structure, where each index entry points to a specific location on-disk. Using a B-tree structure also means that a MongoDB index is stored in a sorted order, always traversed in-order, and is cheap for MongoDB to fetch a series of documents in a sorted order via indexes. … Read more
Don’t use insert. Use update with upsert=true. Update will look for the document that matches your query, then it will modify the fields you want and then, you can tell it upsert:True if you want to insert if no document matches your query. db.collection.update( <query>, <update>, { upsert: <boolean>, multi: <boolean>, writeConcern: <document> } ) … Read more