Can you recommend a database that scales horizontally? [closed]

Question

Generally the database server is the biggest, most expensive box we have to buy as scaling vertically is the only option. Are there any databases that scale well horizontally (i.e. across multiple commodity machines) and what are the limitations in this approach?

Answer 1

MongoDB is one of the best database that scales horizontally.

Answer 2

Oracle RAC is not horizontally scalable at all, because all Oracle instances share the same data storage. Yes, with SAN stuff u can get a large size DB, but it's just not scalable at all. In other words, Oracle RAC is still a scale-up approach. So for scaling-out or horizontally scaling, you have to partition your data by function that means put different groups of tables in different databases; or partition your data per table that means partition one table into multiple subtables with the same schema but store in different databases. In this way, you get a scaling-out solution. There are many resources on that. Sharding has been a buzz word for a while in web 2.0 website architecture blog sphere. Because Sharding is not directly supported by database itself, you have to build your own solution. But as I said, there are many lessons already. For oracle, partitioning table is possible. For mysql, check this question