A while back,a Digg developer had posted this blog ,"http://about.digg.com/blog/looking-future-cassandra", where the he described one of the issues that were not optimally solved in MySQL. This was cited as one of the reasons for their move to Cassandra.
I have been playing with MongoDB and I would like to understand how to
implement the MongoDB collections for this problem
From the article, the schema for this information in MySQL :
CREATE TABLE Diggs (
id INT(11),
itemid INT(11),
userid INT(11),
digdate DATETIME,
PRIMARY KEY (id),
KEY user (userid),
KEY item (itemid)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
CREATE TABLE Friends (
id INT(10) AUTO_INCREMENT,
userid INT(10),
username VARCHAR(15),
friendid INT(10),
friendname VARCHAR(15),
mutual TINYINT(1),
date_created DATETIME,
PRIMARY KEY (id),
UNIQUE KEY Friend_unique (userid,friendid),
KEY Friend_friend (friendid)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
This problem is ubiquitous in social networking scenario implementation. People befriend a lot of people and they in turn digg a lot of things. Quickly showing a user what his/her friends are up to is very critical.
I understand that several blogs have since then provided a pure RDBMs solution with indexes for this issue; however I am curious as to how this could be solved in MongoDB.
