mongodb delete old chat

I want to delete old chat logs, meaning any records besides the 10 latest.

Here's how I'm getting the latest:

collection.find({"chatroom" : chatroom}).limit(10).sort({ time: -1 })

H开发者_高级运维ow do I delete everything else?

Thanks.

You can do a query to get the 10th oldest and then delete the ones older than that.

var oldest = find({"chatroom" : chatroom}).limit(1).skip(10).sort({ time: -1 }).next();
remove({"chatroom" : chatroom, time : {$lt : oldest.time }})

You have to iterate over each items of the result set and remove it individually if you get hold of the related documents through a proper filter.

How about using a capped collection?

Reserve enough space in size argument and set max to 10.

You might want to swtich sort({ time: -1 }) with sort({ $natural: -1 }) for better performance if you switch to a capped collection (where both orders would be the same I guess).

How frequently you need to do this? How many docs are we talking about?

One of the option: move the latest 10 to some temp collection empty the log collection reinsert from the temp collection

This might not be the optimal solution.