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What do you mean? Who are they? And what was moved?

@@vladmihalcea well when i try adding the dependency in my pom it didnt work the artifactId "hypersistence-optimizer" wasn't available but instead i found "hypersistence-utils-hibernate-60" in maven so when i try with this it was not there. So i thought it migh be moved to someplace else in the utils...i think i need to look around more And i think they is you😅

@@howto...6298 The project is not open source, so it's not on Maven Central. You have to install it from the package you downloaded from Teachable, following the links from my website.

I'm glad you liked it. This video is part of my High-Performance Java Persistence video course, so if you liked this video, you are going to love the video course. vladmihalcea.com/courses/high-performance-java-persistence/

​@@vladmihalcea I am convinced that your course is flawless and will provide invaluable experience for students, beginners and experienced staff. Thank you for sharing your expertise. The future lies with smart and kind people. You're part of the future, Vlad.

You're welcome. I'm glad I could help.

Yes, you can. Check out this article for more details: vladmihalcea.com/one-to-many-dto-projection-hibernate/ If you prefer a video explanation, then check out my video course as well: vladmihalceastore.teachable.com/p/high-performance-java-persistence-online

@@vladmihalcea very nice article i got it now thank you so much

You're welcome. This video is an episode of my High-Performance Java Persistence video course. If you liked the video, you are going to love the 11-hour video course vladmihalcea.com/courses/high-performance-java-persistence/

You're welcome. If you liked this snippet, you are going to love the video course where this snippet is coming from: vladmihalcea.com/courses/high-performance-java-persistence/

Thanks and stay tuned for more

Thanks. This video is a lesson from my HIgh-Performance SQL video course, so if you liked it, you are going to love the video course. vladmihalceastore.teachable.com/p/high-performance-sql-online?coupon_code=BLACKFRIDAY23

In Europe, where I live, many countries use the 0-10 grade system, where 10 is the highest score. www.nuffic.nl/en/education-systems/european-baccalaureate/grades-and-study-results Hence, the example in this video.

You can map the intermediary table as an entity and get both the convenience of the entity relationship and the flexibility of adding new columns and get the same performance of doing the operations manually.

@@vladmihalcea Thanks for your reply. I don't have the finite opinion on that, but anyways... I'm not sure, that auxiliary table will address complexity issues here... I may be wrong, but it seems simpler to just create two parent entities without any *ToMany relations inside, and the one entity representing join table with one-to-one relation on these parents. In my view, add/remove of both parents and relations between them should be much easier in this regard, as well as understanding of the code. Of course, not everything is cloudless with such an approach. For instance, I'm predicting a lot of troubles with further conversion of the retrieved entities into DTO/JSON to propagate it further as a REST API response: if we had *ToMany parent-child entity, it will be converted into one JSON automatically keeping "children" field as an array of relations. But in case of separate entities, you should do extra activities to compile different entity objects into one DTO/JSON.

@@Exterminator131 You don't need to convert entities to DTOs. You can simply extract Hierarchical DTOs directly from the DB, as I explained in this article vladmihalcea.com/one-to-many-dto-projection-hibernate/ Fetching entities only to discard what you don't need and create a DTO is wasteful. If you think that avoiding the collections is easier for you, then you should not map the associations. In the end, any collection can be replaced with a query.

I'm glad you liked it

You're welcome. If you liked this episode, you are going to love my High-Performance SQL video course.

You can create a different DTO for each specific use case. If you have 5 different use,cases, you create 5 DTOs. Or, you can use the Spring Data JPA interface-based projection and avoid creating the DTO classes.

I don't see how the same join table could ever be used to store multiple FK sets for different parent sets.

Hi @vladmihalcea , Thank you for the prompt reply. Let's say I am storing roles for a tenant and the associated user. so my join table will have user_id, role_id and tenant_id and some extra colums. My question was, can we apply the same logic as suggested in the video in this case too?

I am using the same mapping as suggested in the video, for my case as well, just wanted to know if there are better ways than this.

@@Abhishekchandel008 Your join table can have extra columns and extra associations. Check out my High-Performance Java Persistence video course for more details: vladmihalcea.teachable.com/p/high-performance-java-persistence-mach-3-online

@@Abhishekchandel008 There's always a better way. However, that requires analyzing your schema and the business requirements. Luckily, I do offer consulting if your company is interested in improving their codebase.

When the DB schema is built, it first tries to drop the tables. If there is no such table, the DROP will not work, but the failure is skipped since it's not an issue. As long as the tests run, everything runs as expected.

Cool, so I just need to adjust the logs to debug.

I'm glad you liked it and stay tuned for more

What happen if there are 2 READ/SELECT transactions happen at the same times?

The second transaction can be anything.

@@vladmihalcea sorry, i need to ask you. On that article, you said pessimistic/serializable does not solve Lost Update problem, could you explain it further?

@@romarioputra3775 You can find a more detailed explanation in the Transaction module of my High-Performance Java Persistence video course vladmihalcea.teachable.com/p/high-performance-java-persistence-mach-3-online

You can find a detailed explanation of your question in my High-Performance Java Persistence video course. Enjoy watching almost 11 hours of video lessons: vladmihalcea.teachable.com/p/high-performance-java-persistence-mach-3-online

Why would I do that?

Yes, of course. Check out this article for more details vladmihalcea.com/one-to-many-dto-projection-hibernate/

@@vladmihalcea thank you very much.

@@vladmihalcea If I have 5 collections in entity, and that collections have nested collections, than I want to fetch all that fields. Can you help to find answer for that? Thank you.

@@user-cr5kz9nb5d You can do it like this github.com/vladmihalcea/high-performance-java-persistence/blob/master/core/src/test/java/com/vladmihalcea/book/hpjp/hibernate/fetching/multiple/MultiLevelCollectionFetchingTest.java#L108

SQL is a declarative language. You're analyzing the query definition using a procedural mindset. That's why it confused you. What you need to do is run EXPLAIN ANALYZE on the query and see exactly the stream operations done by the DB when executing the query.

@@vladmihalcea Thanks Vlad, will try to explore more. anyway subcribed to your channel to see more useful contents.

You're welcome

On my latest videos, I increased the volume.

I'm glad you liked it

@@vladmihalcea Your videos are excellent, well explained with high quality image, etc. But if they all have the same title, how do I know the order? For example: Part 1, Part 2, etc? Thank you.

@@Jody-nf2bz In the description of every video, you will find information about the previous and next videos in the series. However, you can watch them in any order as each one is dedicated to a specific topic.

@@vladmihalcea Thank you.

@@Jody-nf2bz You're welcome. Enjoy watching them!

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It's easier if you use Docker to run the DB on tmpfs. This works no matter what host OS you use. vladmihalcea.com/how-to-run-integration-tests-at-warp-speed-with-docker-and-tmpfs/

@@vladmihalcea Got it, another question on the android phone is there any app for me to create tmpfs or ramfs?

@@vagnerdasilva1652 For SQLite on Android?

@@vladmihalcea Is this SQLite the name of the application that you said you have in the Play Store?

@@vagnerdasilva1652 I didn't say anything about Play Store. It's unlikely that you need tmpfs for Android.

You're welcome

Thanks and stay tuned for more

Prepare yourself to be amazed 🚀

You're welcome

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The class diagrams were generated with IntelliJ IDEA. The DB table diagrams with MySQL Browser. The rest of the diagrams were generated with yEd.

You're welcome and stay tuned for more

I use Blaze Persistence instead of Criteria API: vladmihalcea.com/blaze-persistence-jpa-criteria-queries/ QueryDSL was abandoned for many years, and only currently got some updates. For native SQL, I'd rather use jOOQ, as it's superior to QueryDSL in any way.

@@vladmihalcea It seams Blaze does not give TypeSafe queries like QueryDSL, what is other disadvantage of QueryDSL beside not being maintained actively ?

@@vaheharutyunyan966 Blaze Persistence has typed queries using the JPA Metamodel vladmihalcea.com/bulk-update-delete-blaze-persistence/ However, jOOQ is even more powerful than Blaze. You can even use it to fetch efficiently multiple one-to-many relations without a Cartesian Product: blog.jooq.org/jooq-3-15s-new-multiset-operator-will-change-how-you-think-about-sql/ It's also amazing for stored procedures too: vladmihalcea.com/jooq-facts-sql-functions-made-easy/ Plus, it offers Keyset Pagination, Recursive CTE, Pivot, Window Functions, Lateral Joins, JSON, and many more features. And it's maintained and improved constantly.

You're welcome

Which feature are you talking about?

@@vladmihalcea I mean one to one relationship without n+1 problem which you described in video

@@aleemkhowaja2274 The solution for that can be done with a Maven or Gradle plugin that it's independent of Spring. So, it works I the same way with Spring as it does with Java EE.

@@vladmihalcea ahh ok yaah makes sense to me thanks bro btw great explanation in video and thank you so much for response cheers 🥂 🙂

@@aleemkhowaja2274 You're welcome. If you liked this video, there's a 40% discount on the video course: vladmihalcea.teachable.com/p/high-performance-java-persistence-mach-3-online/?coupon_code=BLACKFRIDAY22 But hurry up! It expires in 2 days.

I'm glad you liked it. In fact, you are going to love the video course even more. As for your question, the entity that maps the FK column is the one that should own the relation because FK column values are supposed to be managed via their associated table record.

Thanks. I'm glad you liked it. You can find more information about the topic and details about when to use one strategy or the other in my High-Performance Java Persistence video course. vladmihalcea.com/courses/high-performance-java-persistence/ It features 11 hours of video lessons that you are going to love even more than this sample.

Thanks

I will. Subscribe to get the update.

Thank you so much sir ❤️

Actually, you can do that using Blaze Persistence. persistence.blazebit.com/documentation/1.5/entity-view/manual/en_US/#basic-mappings It's OSS and extremely powerful. It's like a JPA plugin that provides additional features.

@@vladmihalcea Oh that's good to know, I'll try this out :) Thanks

@@jkickic It's a really useful framework. I'm using it to write advanced Criteria queries that are way more readable than the default Criteria API. vladmihalcea.com/blaze-persistence-jpa-criteria-queries/ And you can also use it for Keyset Pagination with Spring Data JPA: vladmihalcea.com/keyset-pagination-spring/

Thanks and stay tuned for more

Thanks. I'm glad you liked it. This is part of my High-Performace SQL video course, so if you liked it, you are going to love the entire course. vladmihalcea.com/courses/high-performance-sql/

That's a very good question that I frequently get during my training. The @OneToOne relationship basically maps the one-to-one table relationship that was designed 40 years ago and which serves plenty of use cases, like the following ones: - if you have a JSON column that's large, you might not want to fit it on the same page as the original record as that could create page splits, increase the volume of data that gets synced to the disk when the pages get dirty - if you have columns that have different change frequencies, you can split them by write access patterns so that you could have the columns that frequently change in a separate table whose pages get synced often, but they leave the other table pages to reside in the Buffer Pool - to implement the JOINED table inheritance strategy - to split a large table into multiple ones to increase write scalability as UPDATEs and DELETEs take locks at record level in relational databases, and once you change a single column, the entire record gets locked until you commit or roll back. But by splitting the original table into several tables, you can increase the write throughput. - to reduce the optimistic locking conflicts as you have multiple version columns in multiple tables. If you only have a single table, then any column change will cause the other concurrent transactions that also want to change the same record to abort after the first transaction has bumped the version up.

Thanks and stay tuned for more

Thanks, Piotr. Stay tuned for more!

Thanks and stay tuned for more