fix a diagram and add alt text

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Gavin 2023-05-18 12:57:53 +02:00 committed by Christian Beikov
parent e846fd88d9
commit edb0a27197
6 changed files with 7 additions and 6 deletions

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@ -934,16 +934,17 @@ An association between entity classes may be either:
- _unidirectional_, navigable from `E` to `F` but not from `F` to `E`, or
- _bidirectional_, and navigable in either direction.
In this diagram, we can see the sorts of associations which are possible.
In this example data model, we can see the sorts of associations which are possible:
image::images/associations.png[]
image::images/associations.png[Example data model,align="center",pdfwidth=90%]
[TIP]
// .One-to-one associations and subtyping
====
An astute observer of the diagram above might notice that the relationships we've represented as unidirectional one-to-one associations could reasonably be represented in Java using subtyping.
An astute observer of the diagram above might notice that the relationship we've presented as a unidirectional one-to-one association could reasonably be represented in Java using subtyping.
This is quite normal.
A one-to-one association is the usual way we implement subtyping in a fully-normalized relational model.
It's related to the `JOINED` <<mapping-inheritance,inheritance mapping>> strategy.
====
There are three annotations for mapping associations: `@ManyToOne`, `@OneToMany`, and `@ManyToMany`.

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@ -48,7 +48,7 @@ Thus, an entity instance may be in one of three states with respect to a given p
2. _persistent_ — currently associated with the persistence context, or
3. _detached_ — previously persistent in another session, but not currently associated with _this_ persistence context.
image:images/entity-lifecyle.png[width=800,align="center"]
image::images/entity-lifecyle.png[Entity lifecycle,width=800,align="center"]
At any given moment, an instance may be associated with at most one persistence context.

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@ -57,7 +57,7 @@ We can think of the API of Hibernate in terms of three basic elements:
- a _native API_ exposing the full set of available functionality, centered around the interfaces `SessionFactory`, which extends `EntityManagerFactory`, and `Session`, which extends `EntityManager`, and
- a set of _mapping annotations_ which augment the O/R mapping annotations defined by JPA, and which may be used with the JPA-defined interfaces, or with the native API.
image::images/api-overview.png[width=700,align="center"]
image::images/api-overview.png[API overview,width=700,align="center"]
As an application developer, you must decide whether to:

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@ -108,7 +108,7 @@ fundamental rule of thumb in ORM is:
of a session/transaction, and fetch it immediately in one or two queries,
- and only then start navigating associations between persistent entities.
image:images/fetching.png[width=700,align="center"]
image::images/fetching.png[Fetching process,width=700,align="center"]
Without question, the most common cause of poorly-performing data access
code in Java programs is the problem of _N+1 selects_. Here, a list of N

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