[Rails] Re: working with models, efficent queries..

On Tuesday, December 10, 2013 8:29:17 PM UTC, Colin Williams wrote:

 i have a model with 35000 entries in the database. I was using a unique string as the primary key. Right now I am using the order method to return the model objects in
 order. I'd like to know what is good practice ( efficient ) and how to return X entries at a time instead of all at once. Right now I'm using the index method of a controller along with the order method to return the entries, and then iterating through them in the view.

Typically you load one page of results at a time. kaminari and will_paginate are 2 popular ways of doing this. Under the hood they are just setting limit and offset query 

I'd also like to know a little more about how conrtrollers work with the database. Is a new store controller instanced everytime a route is directed to it? If so am I continually querying the database for those 35000 entries, or is one instance of the controller generated, and one request made. I have read some of the rails guides, and read quite a bit of agile web dev with rails 4, but haven't found the answer to my questions. Do

a new controller is instantiated with each request. so your code hits the database for every single page view (which you can easily prove to yourself by adding a breakpoint or logger statements to the body of your controller method or watching the queries stack up in the log file

Fred

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