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fix wording in eager loading docs

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Improve wording of a couple of subsections in the **Eager Loading Associations** portion of these docs. It appeared some sections had been copy/pasted and not updated to refer to the method they were actually talking about.
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Jon Kulton 2022-01-17 12:07:26 -05:00
parent 9fb6cdf8fa
commit e12908ea40
1 changed files with 10 additions and 10 deletions
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guides/source/active_record_querying.md
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@ -1409,10 +1409,10 @@ books.each do |book|
end end
``` ```
The above code will execute just **2** queries, as opposed to **11** queries in the previous case: The above code will execute just **2** queries, as opposed to the **11** queries from the original case:
```sql ```sql
SELECT `books`* FROM `books` LIMIT 10 SELECT `books`.* FROM `books` LIMIT 10
SELECT `authors`.* FROM `authors` SELECT `authors`.* FROM `authors`
WHERE `authors`.`book_id` IN (1,2,3,4,5,6,7,8,9,10) WHERE `authors`.`book_id` IN (1,2,3,4,5,6,7,8,9,10)
``` ```
@ -1473,9 +1473,9 @@ This is because it is ambiguous whether they should appear on the parent record,
### preload ### preload
With `preload`, Active record ensures that loaded using a query for every specified association. With `preload`, Active Record loads each specified association using one query per association.
Revisiting the case where N + 1 was occurred using the `preload` method, we could rewrite `Book.limit(10)` to authors: Revisiting the N + 1 queries problem, we could rewrite `Book.limit(10)` to preload authors:
```ruby ```ruby
@ -1486,19 +1486,19 @@ books.each do |book|
end end
``` ```
The above code will execute just **2** queries, as opposed to **11** queries in the previous case: The above code will execute just **2** queries, as opposed to the **11** queries from the original case:
```sql ```sql
SELECT `books`* FROM `books` LIMIT 10 SELECT `books`.* FROM `books` LIMIT 10
SELECT `authors`.* FROM `authors` SELECT `authors`.* FROM `authors`
WHERE `authors`.`book_id` IN (1,2,3,4,5,6,7,8,9,10) WHERE `authors`.`book_id` IN (1,2,3,4,5,6,7,8,9,10)
``` ```
NOTE: The `preload` method using an array, hash, or a nested hash of array/hash in the same way as the includes method to load any number of associations with a single `Model.find` call. However, unlike the `includes` method, it is not possible to specify conditions for eager loaded associations. NOTE: The `preload` method uses an array, hash, or a nested hash of array/hash in the same way as the `includes` method to load any number of associations with a single `Model.find` call. However, unlike the `includes` method, it is not possible to specify conditions for preloaded associations.
### eager_load ### eager_load
With `eager_load`, Active record ensures that force eager loading by using　`LEFT OUTER JOIN` for all specified associations. With `eager_load`, Active Record loads all specified associations using a `LEFT OUTER JOIN`.
Revisiting the case where N + 1 was occurred using the `eager_load` method, we could rewrite `Book.limit(10)` to authors: Revisiting the case where N + 1 was occurred using the `eager_load` method, we could rewrite `Book.limit(10)` to authors:
@ -1510,7 +1510,7 @@ books.each do |book|
end end
``` ```
The above code will execute just **2** queries, as opposed to **11** queries in the previous case: The above code will execute just **2** queries, as opposed to the **11** queries from the original case:
```sql ```sql
SELECT DISTINCT `books`.`id` FROM `books` LEFT OUTER JOIN `authors` ON `authors`.`book_id` = `books`.`id` LIMIT 10 SELECT DISTINCT `books`.`id` FROM `books` LEFT OUTER JOIN `authors` ON `authors`.`book_id` = `books`.`id` LIMIT 10
@ -1519,7 +1519,7 @@ SELECT `books`.`id` AS t0_r0, `books`.`last_name` AS t0_r1, ...
WHERE `books`.`id` IN (1,2,3,4,5,6,7,8,9,10) WHERE `books`.`id` IN (1,2,3,4,5,6,7,8,9,10)
``` ```
NOTE: The `eager_load` method using an array, hash, or a nested hash of array/hash in the same way as the `includes` method to load any number of associations with a single `Model.find` call. Also, like the `includes` method, you can specify the conditions of the eager loaded association. NOTE: The `eager_load` method uses an array, hash, or a nested hash of array/hash in the same way as the `includes` method to load any number of associations with a single `Model.find` call. Also, like the `includes` method, you can specify conditions for eager loaded associations.
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