We have a big table with a lot of columns. After we moved to MySQL Cluster, the table cannot be created because of: ERROR 1118 (42000): Row size too large. The maximum row size for the used table type, not counting BLOBs, is 14000. This includes storage overhead, check the manual. You have to change some colu…
Tag: orm
What’s the difference between JPA and Spring Data JPA?
I am a bit confused about the difference between Spring Data-JPA and JPA. I know about JPA that it is a specification for persisting the Java Objects to a relational database using popular ORM …
How to paginate a JPA Query
I have a submission table with columns like ID, Name, Code among other properties. My requirement is to search for records based on the mentioned properties and return a paginated set. This is the pseudocode for what I am looking for: There seem to be many options like CriteriaBuilder, NamedQuery, etc. Which …
Hibernate faster EntityManagerFactory creation
In my desktop application new databases get opened quite often. I use Hibernate/JPA as an ORM. The problem is, creating the EntityManagerFactory is quite slow, taking about 5-6 Seconds on a fast machine. I know that the EntityManagerFactory is supposed to be heavyweight but this is just too slow for a desktop…
hibernate or oracle support for timelines?
We have a requirement for persisting, using Hibernate, versioned Java objects into an Oracle database such that each version has a valid-from and valid-until timestamp. This is so we can query for objects as-at a specific time. Does Hibernate or Oracle 11g (or anything else) provide anything that would simpli…
How to use object oriented programming with Hibernate?
While using ORM tools such as Hibernate, I’ve found it is advantageous to keep all business logic out of my business objects and instead keep it in a service layer. The service layer creates the business object POJOs, manipulates them, and uses DAOs to save them. But isn’t this in a way taking a s…
How does Hibernate detect dirty state of an entity object?
Is it using some kind of byte codes modification to the original classes? Or, maybe Hibernate get the dirty state by compare the given object with previously persisted version? I’m having a problem with hashCode() and equals() methods for complicated objects. I feel it would be very slow to compute hash…
How to specify SQL comments through JPA annotations?
Is there any way to specify SQL comments through JPA annotations? Comments for tables and columns. Answer Is there any way to specify SQL comments through JPA annotations? Comments for tables and columns. No. If you want to define tables and columns comments, your best option is to do it after the facts in th…
Hibernate : dynamic-update dynamic-insert – Performance Effects
Using dynamic-update or dynamic-insert has positive, though generally slight only on performance, as also mentioned by http://www.mkyong.com/hibernate/hibernate-dynamic-update-attribute-example/ But the reference documentation mentions that this could have negative performance effects also as mentioned below …
Difference between FetchType LAZY and EAGER in Java Persistence API?
What is the difference between FetchType.LAZY and FetchType.EAGER in Java Persistence API? Answer Sometimes you have two entities and there’s a relationship between them. For example, you might have an entity called University and another entity called Student and a University might have many Students: …