How many databases can I create on a single Amazon RDS instance

Question

How many databases can I create on a single Amazon RDS instance?

I need to move from Xeround to another server (they are closing for public clouds). My two options are either create a single EC2 instance with EBS backed (10,000 iOPS) or RDS. I have three databases and not too much traffic. If I need to launch RDS instance for each database it can be a bit too expensive for me.

Answer 1

http://aws.amazon.com/rds/faqs/#2

Multiple MySQL databases or SQL Server databases (up to 30) or Oracle database schemas can be created on a given DB Instance.

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Update 2013-12-16: as discussed in the comments below, the wording in the RDS FAQ is ambiguous. @Jan sent an inquiry to Amazon, and got this reply:

With RDS MySQL database instances, it follows the MySQL standard where there's no limit on the number of databases - http://dev.mysql.com/doc/refman/5.5/en/database-count-limit.html. Thank you for pointing out the spotty documentation there, we'll amend that to make it more clear.

Thanks @Jan!

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Update 2014-08-26: the RDS FAQ now states:

• RDS for MySQL: No limit imposed by software
• RDS for Oracle: 1 database per instance; no limit on number of schemas per database imposed by software
• RDS for SQL Server: 30 databases per instance
• RDS for PostgreSQL: No limit imposed by software

And that makes one wonder, "how many instances can I have?"

By default, customers are allowed to have up to a total of 40 Amazon RDS DB instances. Of those 40, up to 10 can be Oracle or SQL Server DB Instances under the "License Included" model. All 40 can be used for MySQL, Oracle, SQL Server, or PostgreSQL under the "BYOL" model. If your application requires more DB Instances, you can request additional DB Instances via this request form.