Time Complexity of $addToset vs $push when element does not exist in the Array

Question

Given: Connection is Safe=True so Update\'s return will contain update information.

Say I have a documents that look like:

[{\'a\': [1]}, {\'a\': [2]}, {         


        

Answer 1

Adding my observation in difference between addToSet and push from bulk update of 100k documents.

when you are doing bulk update. addToSet will be executed separately.

for example,

bulkInsert.find({x:y}).upsert().update({"$set":{..},"$push":{ "a":"b" } , "$setOnInsert":  {} })

will first insert and set the document. And then it executes addToSet query.

I saw clear difference of 10k between

db.collection_name.count() #gives around 40k 

db.collection_name.count({"a":{$in:["b"]}}) # it gives only around 30k

But when replaced $addToSet with $push. both count query returned same value.

note: when you're not concerned about duplicate entry in array. you can go with $push.