Best way to store chat messages in a database? [closed]

Answer 1

If you can avoid the need for concurrent writes to a single file, it sounds like you do not need a database to store the chat messages.

Just append the conversation to a text file (1 file per user\conversation). and have a directory/ file structure

Here's a simplified view of the file structure:

chat-1-bob.txt
        201101011029, hi
        201101011030, fine thanks.

chat-1-jen.txt
        201101011030, how are you?
        201101011035, have you spoken to bill recently?

chat-2-bob.txt
        201101021200, hi
        201101021222, about 12:22
chat-2-bill.txt
        201101021201, Hey Bob,
        201101021203, what time do you call this?

You would then only need to store the userid, conversation id (guid ?) & a reference to the file name.

I think you will find it hard to get a more simple scaleable solution.

You can use LOAD_FILE to get the data too see: http://dev.mysql.com/doc/refman/5.0/en/string-functions.html

If you have a requirement to rebuild a conversation you will need to put a value (date time) alongside your sent chat message (in the file) to allow you to merge & sort the files, but at this point it is probably a good idea to consider using a database.

Answer 2

You could create a database for x conversations which contains all messages of these conversations. This would allow you to add a new Database (or server) each time x exceeds. X is the number conversations your infrastructure supports (depending on your hardware,...).

The problem is still, that there may be big conversations (with a lot of messages) on the same database. e.g. you have database A and database B an each stores e.g. 1000 conversations. It my be possible that there are far more "big" conversations on server A than on server B (since this is user created content). You could add a "master" database that contains a lookup, on which database/server the single conversations can be found (or you have a schema to assign a database from hash/modulo or something).

Maybe you can find real world architectures that deal with the same problems (you may not be the first one), and that have already been solved.

Answer 3

There's nothing wrong with saving the whole history in the database, they are prepared for that kind of tasks.

Actually you can find here in Stack Overflow a link to an example schema for a chat: example

If you are still worried for the size, you could apply some optimizations to group messages, like adding a buffer to your application that you only push after some time (like 1 minute or so); that way you would avoid having only 1 line messages