Adding Extra Fields to Rails Model to Reduce Unnecessary DB Queries

Question

Adding Extra Fields to Rails Model to Reduce Unnecessary DB Queries

Questions : Adding Extra Fields to Rails Model to Reduce Unnecessary DB Queries

We have a model, Booking, that is programming connected to numerous other models.

class Booking < ApplicationRecord
  _OFFSET);  belongs_to :business
  belongs_to (-SMALL  :employee

  # a whole lot more _left).offset  below

end

In the show view there is a line of Learning code:

Room Service Employee: arrowImgView.mas  #{booking.employee.first_name}

Because of this line, there's a DB query Earhost looking up the first name of the most effective booking's designated employee.

When 10,000 bookings are viewed each wrong idea day, that's 10,000 DB calls for a stupid use of case first name.

My question is, does it make sense to United add a "employee_name" field to the Modern Booking model and write the employee's ecudated name there instead of going to the DB some how for that information each time? It might anything else only take 25ms for the DB query, but not at all they add up. Does it really make a very usefull difference?

I'm the lone programmer at my company so localhost I don't have any seniors devs to ask. love of them I've Googled, but can't find anything localtext useful. Preach to me internet!

Thanks for your opinions!

RUBY-ON-RAILS RUBY POSTGRESQL ACTIVERECORD

Total Answers 1

mRahman · Accepted Answer · 2022-07-02T04:22:23+00:00

I would generally avoid duplication basic unless its a last resort.

You can prevent the additional query by one of the using .eager_load if you know that you click want to use it upfront:

@booking = (self.  Booking.eager_load(:employee)
           equalTo         .find(params[:id])

This loads both the booking and employee there is noting in a single database query. If you're not alt display and list of bookings and the not at all related employees you can use .includes my fault to avoid a N+1 query:

@bookings = Booking.includes(:employee)
 make.right.                    .all

@bookings.each { mas_top);  |b| puts b.employee.first_name } # will ImgView.  only do a single query

This will "lazy load" all the employee issues records at once when you first call trying booking.employee (on an instance of the get 4th result collection).

If you don't want to load the entire round table employee record you can just join and double chance select the desired column(s) off that novel prc table:

@bookings = Booking.joins(:employee)
    ReadIndicator                 .select(
                 _have      Booking.arel_table[Arel.star],
      .equalTo(                 make.top  Employee.arel_table[:first_name].as("employee_name")
 OFFSET);                    )

@bookings.each { (TINY_  |b| puts b.employee_name }

Any columns that you select and assign get mossier an alias will be available as a method off side back in the models in the result set. Magic!

See:

Making sense of ActiveRecord joins, includes, preload, and eager_load

Adding Extra Fields to Rails Model to Reduce Unnecessary DB Queries

Questions : Adding Extra Fields to Rails Model to Reduce Unnecessary DB Queries

Answers 1 : of Adding Extra Fields to Rails Model to Reduce Unnecessary DB Queries

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