rails refactoring tips

I have been building a large scale rails app and it has come time 开发者_JAVA技巧to refactor it.

What tips can you offer me, or resources can you point me to? I am especially interested in making my database calls more efficient.

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"Making database calls more efficient" is not refactoring, it is performance tuning.

• Do performance tests and look carefully at your logs to help guide you on what to work on first.

• Find out which are your slowest queries and work on them.

Re: Refactoring tips

• Always add the tests first, then refactor. Refactoring without tests is like the high-wire without a net--possible and many do it, but also very dangerous.

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In general, doing the following will give you some performance boosts.

• Use indexes on your database columns such as foreign keys and STI type fields. Basically any field that is used for a join or for searching.
• Use the include argument (method in Rails 3) to eager load associations when needed. This can be a good place where benchmarking will help you figure out if you're improving or hurting performance.
• Specify which fields to select in queries using the select argument. By default it loads all the columns, but limiting to only the fields you need will improve performance. I would only recommend this if you have a table with lots of columns and you are selecting lots of records at once.