When mixing JOIN FETCH and pagination, you might bump into the HHH000104: firstResult/maxResults specified with collection fetch applying in memory issue. If you want predictable response times, limiting the query result sets is the way to go.įor more details about how the query pagination works and why it provides better SQL execution plans, check out this article. Also, data tends to grow with time, and if you are not limiting the query result sets, the amount of data being fetched will grow larger and larger. If the data is meant to be displayed on the UI, there’s already a limit on how much data you can display in one view, so anything else becomes waste which affects application performance. Not only that you should consider the number of columns that you are fetching from the database, but you should limit the number of records as well. Unlike entity fetching, a DTO projection allows you the number of columns that you are fetching from the database, and this can speed up queries significantly. table, trees), and you don’t want to further modify it, then a DTO projection is much more suitable. However, if you only need to display data (e.g. As a rule of thumb, if you want to INSERT, UPDATE or DELETE records, fetching entities is very convenient, especially due to the automatic dirty checking mechanism. More, if you forget to JOIN FETCH an EAGER association in a JPQL or Criteria API query, you’ll end up with an N+1 query issue.įor more details about why you should prefer lazy loading, check out this article.Īnother very important aspect when fetching data with JPA and Hibernate is to differentiate the use cases that need entities versus the ones that can do just fine with a DTO projection. When using Hibernate, there is no way to switch the fetch strategy from EAGER to LAZY even if you are using JPA entity graphs. Right from the very beginning, you should prefer using lazy fetching and keep in mind that and associations are fetched eagerly by default. That’s because JPA makes it very easy to fetch more data than you really need. While getting started with JPA and Hibernate is fairly easy, if you want to get the most out of your data access layer, it’s very important to understand how the JPA provider works, as well as the configuration properties that can help you optimize application performance.Ī MUST read about performance tunning tips -> Thank you !- Víctor Cañizares July 11, 2019įetching too much data is the number one problem that causes performance issues when it comes to using JPA and Hibernate. In this article, I’m going to summarise the most common Hibernate performance tuning tips that can help you speed up your data access layer. So, enjoy spending your time on the things you love rather than fixing performance issues in your production system on a Saturday night! Well, Hypersistence Optimizer is that tool!Īnd it works with Spring Boot, Spring Framework, Jakarta EE, Java EE, Quarkus, or Play Framework. Follow having a tool that can automatically detect JPA and Hibernate performance issues.
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