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Merge pull request #49179 from Shopify/cpk-release-notes

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[ci skip] Add composite primary key release note
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Adrianna Chang 2023-09-07 10:49:57 -04:00 committed by GitHub
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guides/source/7_1_release_notes.md
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@ -150,7 +150,26 @@ and reporting of the bulk enqueuing process.
### Composite primary keys
TODO: Add description
Composite primary keys are now supported at both the database and application level. Rails is able to derive these keys directly from the schema. This feature is particularly beneficial for many-to-many relationships and other complex data models where a single column is insufficient to uniquely identify a record.
The SQL generated by query methods in Active Record (e.g. `#reload`, `#update`, `#delete`) will contain all parts of the composite primary key. Methods like `#first` and `#last` will use the full composite primary key in the `ORDER BY` statements.
The `query_constraints` macro can be used as a "virtual primary key" to achieve the same behavior without modifying the database schema.
Example:
```ruby
class TravelRoute < ActiveRecord::Base
query_constraints :origin, :destination
end
```
Similarly, associations accept a `query_constraints:` option. This option serves as a composite foreign key, configuring the list of columns used for accessing the associated record.
Example:
```ruby
class TravelRouteReview < ActiveRecord::Base
belongs_to :travel_route, query_constraints: [:travel_route_origin, :travel_route_destination]
end
```
### Introduce adapter for `Trilogy`