About fetch


Iterating over large result set

Hi, Few days ago I was writing some code to iterate over quite a large dataset. Fitting those data in memory was quite a challenge even with 3GB heap space. So I did paging using two loops. ... With some JDBC drivers there is a hint, that driver should fetch data in packages of given size until whole result set is iterated.  ... by running the query with a hint "objectdb.result-fetch" set to "LAZY" . Another option is to use a report query, ...



... non standard database file suffixes. Changed fetch of collection elements. Fixed an ... . Fixed a bug in applying nested eager fetch when enhancement is disabled. Fixed the "Annotated methods ... Improved Explorer performance by disabling EAGER fetch. Fixed critical bugs in using flush. Fixed ...


@ElementCollection of type enum

Hi! I have in an entity called User with the following field: @ElementCollection(fetch = FetchType.EAGER) private Set<UserPermission> permissions; package x.x.x.x public enum UserPermission { BASIC, COACH, ADMIN } Use case: there are users which contain the first 2 permissions (BASIC and COACH, so the first 2 entries). ... called User with the following field: @ElementCollection(fetch = FetchType.EAGER) private Set<UserPermission> permissions; ... and BASIC231. Conclusion: @ElementCollection(fetch = FetchType.EAGER) private Set<UserPermission> permissions; saves ...



Instances of the Extent class represent the entire collection of instances in the data store of the candidate class or interface possibly including its subclasses or subinterfaces.(Interface of JDO)



For use with addCategory and removeCategory calls.(Static Field of javax.jdo.FetchGroup)



Return the fetch size, or FETCH_SIZE_OPTIMAL if not set, or FETCH_SIZE_GREEDY to fetch all.(Method of javax.jdo.FetchPlan)



The fetch groups in this fetch plan.(Annotation Element of javax.jdo.annotations.FetchPlan)


EntityManager JPA or JDO impl and different behavior

Hi, I have an issue with the EntityManager. My persistance XML looks like: <?xml version="1.0" encoding="UTF-8"?> <persistence version="2.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"> ... how exactly that map is defined and with which fetch type. If the problem can only be demonstrated in Spring you may ... ( cascade = CascadeType . PERSIST , fetch = FetchType . EAGER ) public ... = CascadeType . ALL , fetch = FetchType . EAGER , orphanRemoval = true ) ...



Set the active fetch groups to the single named fetch group.(Method of javax.jdo.FetchPlan)



Annotation for a group of fetch-group objects(Annotation of JDO)