Superga Women's 2730031 Espadrilles Pink Roses 65 Pink hHq6Afka2

Superga Women's 2730-031 Espadrilles Pink Roses 6.5 Pink hHq6Afka2
  • Outer Material: Cotton
  • Inner Material: Textile
  • Sole: Synthetic
  • Closure: Lace-Up
  • Material Composition: Cotone
  • Shoe Width: normale
Superga Women's 2730-031 Espadrilles Pink Roses 6.5 Pink hHq6Afka2 Superga Women's 2730-031 Espadrilles Pink Roses 6.5 Pink hHq6Afka2
back to main navigation
back to main navigation
back to main navigation
back to main navigation
back to main navigation

Thoughts on Java

You are here: / / 5 ways to initialize lazy associations and when to use them

By Thorben Janssen 5 Comments

Lazy loading of associations between entities is a well established best practice in JPA. Its main goal is to retrieve only the requested entities from the database and load the related entities only if needed. That is a great approach if you only need the requested entities. But it creates additional work and can be the cause of performance problems if you also need some of the related entities.

Let’s have a look at the different ways to trigger the initialization and their specific advantages and disadvantages.

Don’t want to read? You can watch it here!

Lets start with the most obvious and unfortunately also the most inefficient approach. You use the find method on the EntityManager and call a method on the relation.

Tamaris 28301 Women’s Wedge Heel Slingback Sandals Brown Braun Pepper Comb 301 E53FSq
Salabobo Womens Comfort Wedding Character OL Work Dress Piontedtoe Kitten Heel PU Pumps Orange LlsDh2R
hosted with by Gabor Womens 5697331 Loafer Flats Brown Brown Brown 22tBDo

Well, you probably know it. This code performs an additional query to initialize the relation. That doesn’t sound like a real problem, but let’s calculate the number of executed queries in a more real world-ish scenario. Let’s say you have an entity with 5 associations which you need to initialize. So you will get 1 + 5 = 6 queries .

OK, that are 5 additional queries. That still doesn’t seem like a huge issue. But our application will be used by more than one user in parallel (I hope).

Let’s say your system has to server 100 parallel users. Then you will get 100 + 5*100 = 600 queries . That is called the n+1 select issue, and it should be obvious that this is not a good approach. Sooner or later, the number of additionally performed queries will slow your application down. Therefore you should try to avoid this approach and have a look at some other options.

Join the Thoughts on Java Library

Get free access to:

Signup For Free:

Already a member? Login here.

A better option to initialize lazy associations is to use a JPQL query with a fetch join.

view raw hosted with by GitHub

The advantage is that Hibernate fetches everything within one query. From a performance point of view, this is much better than the first approach.

And the main disadvantage is that you need to write additional code which executes the query. But it gets even worse if the entity has multiple associations and you need to initialize different associations for different use cases. In this case, you need to write a query for every required combination of associations you want to initialize. That can become quite messy.

Nike Hypervenom Phelon 3nbsp;DF FG Football Shoes Men Blacknbsp; 49bjIR
Sign In

The Genius of Flexibility Santa Barbara

We are centrally located downtown near Santa Barbara Street and Canon Perdido Street

888-730-7953 x3

Sam Edelman Womens Gigi Sandals Black Patent pl0delDVe
Skechers Women BeverleeHigh Tea Open Toe Sandals Black Black H2pIxJ9Cx
Organic Food Restaurants
Vans Unisex Adults Era 59 Canvas Gum Trainers Red Canvas Gum/ Port Royale/Light Gum 5RO9MD4

The Genius of Flexibility Santa Barbara is housed in the greenest building in Santa Barbara , a Built Green environmentally retrofit 1920s era structure located in the historic Plaza de Alhecama in downtown Santa Barbara.

Located in the quiet park behind La Playa Azul Cafe and Zaytoon restaurant, our 100% solar powered facility is environmentally sensitive and energy efficient, featuring three open air and naturally lit rooms with radiant infrared heating throughout.

The Genius of Flexibility Santa Barbara center embodies our vision of an ideal work space: working inside a structure that is ecologically sound so as to reflect the sustainability we create within a person's body.

September 15-23, 2018 — Level I-III Certification Immersion

ThirtyTwo Groomer FT 13/14 Womens Boots Black/Purple UK 7 GP8hH5uUn

September 18-19, 2018 — Level II Certification

Puma Women’s Enzo NF Mid Wn Sneaker Rock Ridgepearl 6KmEnt

September 24-30, 2018 — Level V Certification

Daily classes avaiable with Bob Cooley, Elite Trainers, and Interns.

Our classes are appropriate for all ages, abilities, and backgrounds. They include lots of physical activity, but you work at your own pace. Learn the unique relationship between resistance, flexibility, and strength while also discovering concomitant physical, spiritual, emotional, and psychological benefits.

Learn more

Private sessions avaiable with Bob Cooley, Elite Trainers, and Interns.

A private session is your appointment for intensive and personalized flexibility training. It starts with a one-on-one stretch program tailored to your body, your needs, and your goals.

Daily self-stretching, assisted stretching, and mashing private sessions, plus more.

Personal retreats are a great option for those who don't live near one of our centers but wish to experience all that Resistance Flexibility can offer. For both locals and visitors from around the globe, our personal retreats offer a comprehensive and concentrated training experience.



CASSIS COTE DAZUR Women’s Yalda Espadrilles Black Noir HBYMDChH