# Large Mysql Database (Multiple Databases?) **URL:** \ **Category:** Rails\ **Created:** [April 18, 2009, 5:18pm UTC](https://www.ruby-forum.com/t/large-mysql-database-multiple-databases/165861 "2009-04-18T17:18:32Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![internetchris](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/i/c68b51/32.png) [@internetchris](https://www.ruby-forum.com/u/internetchris)\ **Post date:** [April 18, 2009, 5:18pm UTC](https://www.ruby-forum.com/t/large-mysql-database-multiple-databases/165861/1 "2009-04-18T17:18:32Z")
Hey Everyone, I’m looking for some advice. I am developing an application that will have several million transaction records. I’ve heard of people scaling Rails to connect to multiple databases. I have never done this, and I’m wondering if rails can look at multiple databases and treat them as one, or if I design some sort of overload feature that makes it trickle from one database to the next. In essence I don’t want my rails application to be limited by database capability or size. As I said before I have never designed an app like this, and I want to get it right before I get too far into the application. I have just started the coding, and would like to be proactive on making the right decision. Thanks! Chris ---
**Author:** ![internetchris](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/i/c68b51/32.png) [@internetchris](https://www.ruby-forum.com/u/internetchris)\ **Post date:** [April 18, 2009, 6:25pm UTC](https://www.ruby-forum.com/t/large-mysql-database-multiple-databases/165861/2 "2009-04-18T18:25:58Z")
You’ll probably want to look at replication [1] and/or sharding. There are several gems out there that will help you do one, the other, or both within Rails. I haven’t used any of them, but some quick googling seem to indicate that data\_fabric [2] or masochism [3] might be good places to start. While googling I also ran across MySQL’s HA/Scalability Guide which looks useful if this is something new to you. dwh [1] [http://dev.mysql.com/doc/refman/5.1/en/replication-solutions.html](http://dev.mysql.com/doc/refman/5.1/en/replication-solutions.html) [2] [http://blog.fiveruns.com/2008/7/9/introducing-data\_fabric](http://blog.fiveruns.com/2008/7/9/introducing-data_fabric) [3] [GitHub - technoweenie/masochism: ActiveRecord connection proxy for master/slave connections](http://github.com/technoweenie/masochism/tree/master) [technoweenie always chooses the best project names…] [4] [http://dev.mysql.com/doc/mysql-ha-scalability/en/index.html](http://dev.mysql.com/doc/mysql-ha-scalability/en/index.html) ---
**Author:** ![internetchris](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/i/c68b51/32.png) [@internetchris](https://www.ruby-forum.com/u/internetchris)\ **Post date:** [April 18, 2009, 8:52pm UTC](https://www.ruby-forum.com/t/large-mysql-database-multiple-databases/165861/3 "2009-04-18T20:52:03Z")
internetchris wrote: […] > In essence I don’t want my > rails application to be limited by database capability or size. I would think that it would be better to have the DB take care of the multi-DB splitting, and have it appear to the Rails app as one DB. > As I > said before I have never designed an app like this, and I want to get > it right before I get too far into the application. I have just > started the coding, and would like to be proactive on making the right > decision. The right decision would almost certainly _not_ be to use mySQL. PostgreSQL is generally more capable and faster. It’s also more extensible. > Thanks! > > Chris ## Best, Marnen Laibow-Koser [http://www.marnen.org](http://www.marnen.org) removed\_email\_address@domain.invalid ---
**Author:** ![internetchris](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/i/c68b51/32.png) [@internetchris](https://www.ruby-forum.com/u/internetchris)\ **Post date:** [April 19, 2009, 5:57am UTC](https://www.ruby-forum.com/t/large-mysql-database-multiple-databases/165861/4 "2009-04-19T05:57:05Z")
I appreciate your replys, I will look into PostgreSQL a little futher. A post from yesterday indicated alot of success with PostgreSQL, so I will probably go with it. One other thing… I’m pretty new to rails, and this question may seem ridiculous, but I must ask. If I keep my fields the same in my migration, and simply change my database.yml file will my views and controllers still work fine? I haven’t done alot of development on this app yet, but anytime I can avoid rewriting code it’s nice. Thanks! Chris On Apr 18, 12:52 pm, Marnen Laibow-Koser \