Sitecore 8.2 installed in my local environment. I was investigating that is analytics/xDB working correctly in my setup. I opened my site with a browser and saved the cookie
SC_ANALYTICS_GLOBAL_COOKIE value for myself and the browser a few pages. I waited that the session ends so that Sitecore flushed the data to
MongoDB. I checked the interactions table in MongoDb and I can find the record where I visited the pages. What I noticed also is that the id of ContactId in that record does not match the one that I took from the cookie in the browser, although the Pages that were visited are correct. I did this a few times to make sure. Also, the Contacts table didn't have the same value.
Looking at the Sitecore documentation I understood that the cookie
SC_ANALYTICS_GLOBAL_COOKIE value should be the same as
ContactId. How come in my case it isn't?