About attribute

forum_thread

Mapped By Fetch is very Slow

Well ! I think i pointed out a HUGE performance issue with mapped-by attribute (yeah again :( ). Here is the test case : 1- Create 100 000 entities with for each 1 entity with @OneToOne(mappedBy attribute) 2- Retrieve only 10 000 for testing 3- Wait ... On my AMD FX 8350, it took 60s Now, go the MyEntity class and remove "mapped-by". You obtain 1 second max of query fetch. ... i pointed out a HUGE performance issue with mapped-by attribute (yeah again :( ). Here is the test case : 1- Create ... entities with for each 1 entity with @OneToOne(mappedBy attribute) 2- Retrieve only 10 000 for testing 3- Wait ... On ...

 
api-jpa

javax.persistence.EntityManager

Interface used to interact with the persistence context.(Interface of JPA)

 
page

Apache License, Version 2.0, January 2004

TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 1. Definitions . "License" shall mean the terms and conditions for use, reproduction, and distribution as defined by Sections 1 through 9 of this document. "Licensor" shal ...

 
tutorial

Step 4: Add a Servlet Class

Explains how to add a servlet that manages persistence using JPA and ObjectDB to an Eclipse Web Application.... is retrieved from the application scope attribute, and then an EntityManager (representing a database connection) ... from the database and stored in the request's "guest" attribute. Then the processing is forwarded to the JSP page (which is presented ...

 
issue

No Entity Class API

Both JPA and JDO are based on accessing and managing data in the database using persistable classes (mainly entity classes in JPA or persistence capable classes in JDO). Sometimes, it might be useful to access data without classes. For example, a tool that finds and replaces strings in the database should be generic and should not be bound to specific entity classes and persistent fields. An API for accessing (and maybe also modifying) data in the database without classes can be useful in some applications.... Instances of the type Type represent persistent object or attribute types. See JavaDoc Reference Page... method, or use ...

 
forum_thread

java 8 LocalDateTime is not working in query

My entity class has a field of type java.time.LocalDateTime. I'm able to persist entities and I'm able to query without datetime field in where clause, but with datetime in where clause doesn't return anything and not exception.   ... ( java. time . LocalDateTime attribute ) { return attribute == null ? null : java. sql . Timestamp . valueOf ( attribute ) ; }   @ Override ...

 
manual

Collections in JPQL and Criteria Queries

Shows how collections and maps can be used in JPQL queries.... method Create a path corresponding to the referenced attribute. See JavaDoc Reference Page... ( "languages" ...

 
issue

JPA Metamodel (JPA 2.0)

The JPA Metamodel API enables examining the classes, fields and properties of the persistent object model, similarly to the Java reflection API. The JPA Metamodel API has a major role in defining queries using the JPA Criteria API.... of the JPA Metamodel API, including all the type and attribute interfaces. See JavaDoc Reference Page... API enables ...

 
manual

JPA Query Expressions (JPQL / Criteria)

Describes JPA query (JPQL / Criteria API) expressions (literals, operators and functions).... method Create a path corresponding to the referenced attribute. See JavaDoc Reference Page... , type type() ...

 
manual

Auto Generated Values

Explains the different strategies for generating auto values (mainly for primary key fields) in JPA.... the sequence. See JavaDoc Reference Page... attribute. It is possible that some of the IDs in a given allocation will not ... A tiny difference is related to the initial value attribute. Whereas the SEQUENCE GenerationType.SEQUENCE enum ...