CODEWITHSUNDEEP
mongodbpymongo
silent_coder
silent_coder

Reputation: 6502

mongodb batch operations Is it possible to order or limit data somehow

Let's assume I have 10000k of users I want to select first 500 users and set golden status for them

Is it possible to do that with mongo batch (bulk) opertions?

Upvotes: 1

Views: 69

Answers (1)

ma08
ma08

Reputation: 3734

You can change multiple documents in tn mongoDB using update. But the query can't use $limit or $orderby. Check this issue. So you will need to write a query(as in find) and update documents. If your schema has the ranking of the users, it is very trivial to do that.

db.users.update({rank:{'$lte':500}},{'$set':{status:'gold'}})

But if you have a score based on which you will rank them, it is not so trivial. There is no batch operation. You will need to have to do it yourself for ex. using forEach()

db.users.find({}).sort({score:-1}).limit(500).forEach(...)

in the forEach you can manually set the golden status.

A shrewd way to avoid this is make a query to know the score of the 500th ranked user and use that to update.

db.users.find({}).sort({score:-1}).skip(499).limit(1)

or

db.users.find({}).sort({score:-1}).skip(500)

I don't how it is done in pymongo. Let us assume that docs is the query output.

fooScore=docs[0].score

or

fooScore=docs[500].score

and

db.users.update({score:{'$gte':{fooScore}},{'$set':{status:'gold'}})

Also you will have to deal differently when users are less than 500. Tinker the strategy for users with same score... Also consider setting an index on rank or score for efficient queries.

Upvotes: 2

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