Question: In my db scheme, I need a autoincrement primary key. How I can realize this feature? 

PS For access to DynamoDB, I use [dynode](https://github.com/Wantworthy/dynode), module for Node.js.

Answer: 
I've had the same problem and created a small web service just for this purpose. See this blog post, that explains how I'm using [stateful.co](http://www.stateful.co) with DynamoDB in order to simulate auto-increment functionality: <http://www.yegor256.com/2014/05/18/cloud-autoincrement-counters.html>

Basically, you register an atomic counter at [stateful.co](http://www.stateful.co) and increment it every time you need a new value, through RESTful API. The service is free.
Create the new `file.js` and put this code:

```
exports.guid = function () {
    function _p8(s) {
        var p = (Math.random().toString(16)+"000000000").substr(2,8);
        return s ? "-" + p.substr(0,4) + "-" + p.substr(4,4) : p ;
    }
    return (_p8() + _p8(true) + _p8(true)+new Date().toISOString().slice(0,10)).replace(/-/g,"");
}

```

Then you can apply this function to the primary key id. It will generate the UUID.