I was practicing twitter\'s system design, I came up with high level table schemas and access patterns for them. , I was thinking of using existing systems like MySQL, MongoDb, Cassandra, DynamDb  But I can\'t decide which database system will be good for storing what type of data.\n\nBelow is what I came up with. I would really appreciate If someone can map table to database and may be put some explanation.\n\n**Schema**\n\n**User**\n* Username\n* Email\n* Country\n* Location\n* Photo\n\n\n**Tweet**\n* Id\n* Owner  User::Username\n* Text content\n* Media\n* Timestamp\n* Like_id Like::id\n* Comment_id Comment::id\n\n\n**Comment**\n* Id\n* Content\n* reply Comment::id\n* tweet_id  Tweet:Id\n\n\n**Like**\n* Id tweet:Id\n* User: Id\n\n\n**Follow**\n* Followee_id User:id\n* Follower:id User::id\n\n\n**Table Access Patterns**\n\n**User**\n* Fetch user data from user name\n\n\n**Tweet**\n* Fetch All the tweets for the user\n\n\n**Comment**\n* Fetch all the comments by tweet id\n* Fetch all the replies by comment id\n\n\n**Like**\n* Fetch count of like for tweet id\n* Fetch all user by tweet id\n\n**Timeline Generation**\n* Follow Table :: Fetch all the user ids followed by user\n* Tweet Table :: Fetch all the tweets made by all this users whose timestamp is greater than X\n

I was practicing twitter\'s system design, I came up with high level table schemas and access patterns for them. , I was thinking of using existing systems like