How to delete documents by query efficiently in mongo?

You can use a query to remove all matching documents

var query = {name: 'John'};
db.collection.remove(query);

Be wary, though, if number of matching documents is high, your database might get less responsive. It is often advised to delete documents in smaller chunks.

Let's say, you have 100k documents to delete from a collection. It is better to execute 100 queries that delete 1k documents each than 1 query that deletes all 100k documents.

You can remove it directly using MongoDB scripting language:

db.mycoll.remove({_id:'your_id_here'});

Would deleteMany() be more efficient? I've recently found that remove() is quite slow for 6m documents in a 100m doc collection. Documentation at (https://docs.mongodb.com/manual/reference/method/db.collection.deleteMany)

db.collection.deleteMany(
   <filter>,
   {
      writeConcern: <document>,
      collation: <document>
   }
)

I would recommend paging if large number of records.

First: Get the count of data you want to delete:

-------------------------- COUNT --------------------------
var query= {"FEILD":"XYZ", 'DATE': {$lt:new ISODate("2019-11-10")}};
db.COL.aggregate([
    {$match:query},
    {$count: "all"}
  ])

Second: Start deleting chunk by chunk:

-------------------------- DELETE --------------------------
var query= {"FEILD":"XYZ", 'date': {$lt:new ISODate("2019-11-10")}};
var cursor = db.COL.aggregate([
    {$match:query},
    { $limit : 5 }
  ])
cursor.forEach(function (doc){
    db.COL.remove({"_id": doc._id});
});

and this should be faster:

var query={"FEILD":"XYZ", 'date': {$lt:new ISODate("2019-11-10")}};
var ids = db.COL.find(query, {_id: 1}).limit(5);
db.tags.deleteMany({"_id": { "$in": ids.map(r => r._id)}});

How to delete documents by query efficiently in mongo?

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