how to append data to an existing key's value in mongodb
mongodb, node-mongodb-native
Solution
The problem is that you are using `save` which overrides the document: last one wins. You should consider using atomic updates with `$push`, perhaps via `findAndModify`.
Problem
For example my data is {'abc':'def'},that has a single key-value; I want this: ``` do something...//data has been changed to {'abc':'defghi'} or {'abc':'['def','ghi']'} ``` And I have used this code in nodejs: ``` var tmp2 = {'userid:location:2013-01-02 15':['092030', '12122.11260E']}; collection.insert(tmp2, {safe:true}, function (err, result) { var i = 0; var a = +new Date(); while(i<300000){ tmp2['userid:location:2013-01-02 15'].push(i); collection.save(tmp2, function () { }) i+=1; } var b = +new Date(); console.log(b-a) }); ``` the save api can replace the same key's value,so use push,I can append data to an exising key's value; But there are some problems: - The push operation was badly performanced.Single save can run 15000/s,but when use push,it's 1500/s. - If I have two clients,both want to append data,the later one will cover the earlier one's data,not append. How can I solve this problem?Is there an API？