Spring/Hibernate optimization: JPA with @OneToOne mapping

Lately I wanted to see how Hibernate actually construct sql statements. And it seems like it makes somtimes unnecessary joins. Those are my playground's results.

Repo: https://github.com/toficzak/social-app

Setup:

Post repository consists of 3 methods:


Sql generated by Hibernate:
How did I measure execution time:

  
Simple select measure

By author id: 1952090.938
By author (User provided): 1048579.671
By author (User not provided): 1021450.464
By custom query: 935087.347

My custom JPA query is the fastest option - it skips whole User join section. But why is it needed at all? Seems like an error in my design.
Lokalizacja: Poland

Komentarze

Prześlij komentarz

Popularne posty z tego bloga

Java EE 8 & Wildfly 17 & RestEasy setup

Introduction Java SE/EE for quite a long time was slow. Not in performace, but in releasing new features. Since that was not a good thing in todays fast and modern world, when almost every week new hot thing comes up, it has had to change. And fortunatelly - it does. Now releases are much, much more frequent. And with Eclipse Foundation taking care of Java (or should I say Jakarta) the future looks bright. But Java SE/EE is nothing more than just a set of specifications. You cannot do a thing with it. You need application server. And this post is all about setting up a basic project with Wildfly, the Redhat's free, widely used and highly customizable application server. Since it is easy now to miss out on new stuff, I am going to user newest Wildfly, which is 17 (Java EE 8 support) with JDK 12 to create simple service. Whole code can be found right here:  https://github.com/KKucharczyk/javaee8-bootstrap Requirements To setup simple application, couple of things are requ...
Czytaj więcej

Testing: jUnit's TemporaryFolder

Testing: jUnit's TemporaryFolder with Simple CSV generator The problem Lately I had a question in my head: how to test a method, which output is a file?  Should I divide creation of file from creation of content and test only the latter part? Well, usually I would like to call a method "generateReport" or retrieveFileByHash(), which encapsulate all file-connected operations and return simple java.io.File. In other words, my service classes looks like this: Interface (like ReportGenerator) one method returns: File Concrete class (like DefaultReportGenerator) one public implementation of interface method, (like generateReport()) returns: File set of private methods returns: whatever is needed to create File With such services, file's content creation is separated from File creation: Interface - ReportGenerator method: generateReport() returns File Concrete Class - DefaultReportGenerator method: implementation of generateRepor...
Czytaj więcej

Two entities coexisting in one table

Obraz
I have stumbled across small problem. I had an abstract class, which aggregated all mutual properties of an object and two concrete classes. One did not need any additional fields, while the other needed another relation. Idea was to create one table and gather both those concrete objects from it. I have never done it before, so it was interesting thing to discover. I was working on Team abstraction. Team is a collection of heroes. But teams can be lead by someone or self-organized, hence I have three classes, like so: Notes: BaseTeam is an abstract class annotated with @MappedSuperclass . Since it is abstract I cannot instantiate it and with annotation all its properties will be passed to class extending it. Team class is a concrete class extending BaseTeam. It inherits all the properties from its superclass and does not define any new. It is annotated with @Entity and @Table with filled name property.  It is important to fill those properties, so concrete class can re...
Czytaj więcej