The benefits of a multi-database web site?

What are the benefits of creating a multi-database site?

Does the size split increase speed?

In what cases would we want more than one connected to a site, and do we r开发者_C百科eally need it?

The only real benefit I can think of is having multiple tables with the same name. That way, you could run a debugging database and a development database with the same tables, but the debugging database has testing information in it, and you can switch over to the development database when it's ready just by changing a single string. You could also use that to perform seamless backups, and many other things. Speed might possibly be improved a bit if you had tons of tables with tons of fields, but probably not by much.

Edit: Actually, if the multiple databases span multiple servers, you could store information for fast access (for example, in a forum you might store the latest threads and the user information) on the local server, and store, for example, archived threads on a high-capacity but slower to access server, which would definitely increase speed and decrease the cost of space on the main server.

I'm not sure what you mean by multi-database. If you're thinking about replication of one dataset across multiple database servers, you'll gain redundancy, and will also have the option of load balancing queries.

Edit: You're mentioning "split of size", which may suggest you're thinking about fragmenting or sharding your dataset. That will reduce the amount of data being down or lost if suffering a crash. It will also spread queries across multiple servers, which will enable you to manage higher load.