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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.

BenMorel
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Liron Harel
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2 Answers2

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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.

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!

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.

Bill Karwin
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  • I interpreted this as virtually unlimited MySQL or Oracle database, but only 30 MS SQL databases. Notice where the "(up to 30)" is placed. – Jeremy Ross Sep 25 '13 at 23:23
  • @JeremyRoss, agreed, it could be more clear. I can't tell exactly what they mean either. – Bill Karwin Sep 26 '13 at 02:14
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    I tried and could create more than 30 MySQL databases on RDS. – Jan Nov 20 '13 at 15:51
  • @Jan That is what they guarantee. Tomorrow they will start enforcing this rules and you possibly may have problems with your 30+ databases. – Andrey Dec 11 '13 at 19:08
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    That's not clear to me from how the FAQ is put. I have created a ticket and asked them to clarify. Will update you as soon as I got a response. – Jan Dec 13 '13 at 10:12
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    This is the response I got: "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." – Jan Dec 16 '13 at 08:54
  • Seems like they updated there FAQ in the meantime. Now it is clearly stated that there is no limit imposed for MySQL databases. Thanks! – bjunix Aug 26 '14 at 19:54
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    @bjunix, thanks for the reminder. I've copied the current answer to my answer above. Cloud services tend to change from season to season, so I made sure to date it this time. – Bill Karwin Aug 26 '14 at 20:07
  • @BillKarwin, thx for updating the answer. But actually your quoted answer concerns the maximum number of "instances". The question concerns the number of databases per instance. This is also answered in the FAQ: Q: How many databases or schemas can I run within a DB Instance? A: 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 – bjunix Aug 27 '14 at 11:38
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    @bjunix, thanks, I failed to notice that. I have included the information above in another edit. – Bill Karwin Aug 27 '14 at 16:09
  • Theres an additional FAQ entry now which is clearer, and linked from the original in this post http://aws.amazon.com/rds/faqs/#134 – Bittarman Jun 07 '16 at 12:16
  • SQL Server limit was raised to 100 as of last year: https://aws.amazon.com/about-aws/whats-new/2019/05/amazon_rds_for_sql_server_increases/ – Gigi Jun 11 '20 at 18:06
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As per the AWS document -

  • RDS for Amazon Aurora: No limit imposed by software
  • RDS for MySQL: No limit imposed by software
  • RDS for MariaDB: 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: Up to 100 databases per instance(The maximum number of databases supported on a DB instance depends on the instance class type and the availability mode—Single-AZ, Multi-AZ Database Mirroring, or Multi-AZ Availability Groups. The Microsoft SQL Server system databases don't count toward this limit.) see here: Amazon RDS SQL Server User Guide
  • RDS for PostgreSQL: No limit imposed by software
Ajit
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