Difference between string and text in rails?

Question

Hi I'm making a new web app using Rails and was wondering what's the difference between string and text? And when should each be used?

Thanks

Answer 1

String translates to "Varchar" in your database, while text translates to "text". A varchar can contain far less items, a text can be of (almost) any length.

For an in-depth analysis with good references check http://www.pythian.com/news/7129/text-vs-varchar/

Answer 2

The difference relies in how the symbol is converted into its respective column type in query language.

with MySQL :string is mapped to VARCHAR(255) - http://guides.rubyonrails.org/migrations.html

:string |                   VARCHAR                | :limit => 1 to 255 (default = 255)  
:text   | TINYTEXT, TEXT, MEDIUMTEXT, or LONGTEXT2 | :limit => 1 to 4294967296 (default = 65536)2

http://www.packtpub.com/article/Working-with-Rails-ActiveRecord-Migrations-Models-Scaffolding-and-Database-Completion

When should each be used?

As a general rule of thumb, use :string for short text input (username, email, password, titles, etc.) and use :text for longer expected input such as descriptions, comment content, etc.

Answer 3

If you are using postgres use text wherever you can, unless you have a size constraint since there is no performance penalty for text vs varchar

There is no performance difference among these three types, apart from increased storage space when using the blank-padded type, and a few extra CPU cycles to check the length when storing into a length-constrained column. While character(n) has performance advantages in some other database systems, there is no such advantage in PostgreSQL; in fact character(n) is usually the slowest of the three because of its additional storage costs. In most situations text or character varying should be used instead

PostsgreSQL manual