Updated February 20, 2023
Introduction to Rails includes
The following article provides an outline for Rails includes. Ruby rails is an application window with several options to make the program user-friendly. Ruby rails include a helper tool that is used to integrate commands. Includes, depending on the usage, there are two methods used and they are preload and eager-load. Includes will not generate N number of SQL for every database; instead, it will sum up all the queries and decrease the backend data generated load. It handles data in an integrated manner. It is useful in generating an application using Ruby rails, where a huge number of data can be handled easily.
What is Rails includes?
During discussions, one of the most characteristic questions is how the includes function in Active Record works, yet many developers are unclear about how it works. As a result, it’s worth mentioning that the method’s behavior is intriguing because it changes depending on the scenario. With includes, Active: Record guarantees that all of the given associations are loaded with the fewest number of queries feasible. As a result, both tables are loaded into memory when a table is queried for data with another table.
How to use Rails includes?
Rails will ensure that all the data are entered with a minimum number of inputs or queries. When the query is gathered from the user, the input data in the table format will be stored in the memory. In a typical scenario, if we have N queries, the system will generate N+1 SQL data in the backend and will be stored in the memory. But will not generate that much SQL data. It will rather group all the queries as a single-parent memory only. Also, includes does not generate a separate query to fetch the data from memory. Even nested queries will not generate N+1 queries. The idea is that N+1 queries are generated only when the coding is inefficient.
Let us take a case of 5 employees; hence, 6 SQL queries will be generated.
We make six database visits since we load employees in the first query and then do five further queries to get each employee’s forms. In other words, where N = 5, N + 1 SQL selects occur.
To generate an include command in rails, open the Ruby rails application and can type the command in the format below.
The next step will be using the appropriate command that will fetch records. In the example, the command will fetch from the user where comments. user_id is nil, as shown.
Rails include problem
The major problem or the limitation in Rails would be the amount of data being used, and we need SQL queries which will also be in huge numbers. Also, it takes more time to load data to establish the relationship.
Let us take a scenario of a blog creation application.
In case we want to include several comments for every item in the list of stories, then the code will be as follows:
In the above code, we can see that we are creating a blog where we would get a list of stories that get many comments as inputs. Therefore, using a simple database call will create multiple SQL queries for every input if we use it.
In such a scenario, we need to use included comments to improve the performance.
So, here we include two comments to execute the function.
In this blog section, you came to know what problem you can use the includes function. But this is at the surface level. But, at times, we may have an experience that includes behaving differently in some scenarios.
Two Methods used in Rails include
Given below are the two methods used:
- Preload
- Eager-load
When to use preload?
We use preload once if we want to get access to associated records. However, if we want to filter records by associated records, we want to choose eager-load; for example, in need to collect the number of comments per article by accessing related information in stories and comments. As a result, the utilized preload is included.
If we changed our query from:
to
A new query will be generated because an eager load will be used instead of preload.
Preload vs Eager-load
Preload is utilized when we wish to access related records, and it runs two queries: one to load main records and the other to load associated records.
It isn’t easy to filter records using connected records (comments) since two distinct queries are run:
We need to notify ActiveRecord that we wish to refer to another table, in this instance, comments; therefore, the references(: comments) component. We just notified ActiveRecord that we wanted to access related records and use them to filter the query, so it wouldn’t have to do two queries.
When preload isn’t an option, the eager load is utilized, which generates a query with a left outer join to fetch articles that fit the criteria but include comments.
Conclusion
So, in this blog, we learned about includes in Ruby rails. There are two methods to use the includes depending on the need. Also, we came to know the need to use the includes function in ruby rails. In the best scenario, if we need to measure the performance of your query in your application, you need to use the most efficient ways. As a general rule, using includes will result in performant code that provides the greatest experience for other developers in your codebase – and, of course, consumers engaging with your apps. Get to know more about Ruby rails, which is helpful to handle N number of datas without getting N+1 number of SQL queries by using Ruby rails.
Recommended Articles
This is a guide to Rails includes. Here we discuss the introduction and how to use Rails includes? Problems and two methods, respectively. You may also have a look at the following articles to learn more –
