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How do I achieve a Deep Fetch using JOIN FETCH?

that I can express one level of eager fetch in JPQL as follows: SELECT c FROM C JOIN FETCH c.bList WHERE c.id=:id But when I attempt to take it to the 2nd level: SELECT c FROM C JOIN FETCH c.bList JOIN FETCH c.bList.aList WHERE c.id=:id I get an error along the lines of: Invalid fetch path


fetch doi.metadata metadata left join fetch metadata.titles titles left join fetch metadata.creators creators left join fetch metadata.descriptions descriptions left join fetch metadata.publishers publishers left join fetch metadata.contributors contributors left join fetch metadata.dates

Left join fetch behaviour doesn't retrieve children?

Hello, I'm a little bit confused about a left join fetch behaviour. In this test case, i try to fetch my 3 children using a left join fetch. But my collection is null after closing the em. It was expected to be fetched before closing the em, no ? In fact, that is the objective of the fetch purpose

Lazy Init / Eager / Join Fetch collection strategy ? What to choose ?

Hello, I'm doing some tests to choose the best collection fetch strategy. I have entities with many ... ,join fetch seems to be the right choice. What about ObjectDb ? The implementation is totally different. Is an "All eager strategy" more efficient that many join fetch ( cartesian product + distinct

LEFT JOIN FETCH over empty embedded collection returns no results

First of all, thank you for promptly implementing JOIN FETCH over nested paths in response ... , but I attempt to LEFT JOIN FETCH all the members of a collection within a (non-existent) member ... where bList is empty, the following works (returns my instance of C): SELECT c FROM C c LEFT JOIN FETCH

How to use JOIN FETCH?

JOIN FETCH to avoid excessive round trips to the database: SELECT c FROM Country c JOIN FETCH c ... addresses (obviously fetched lazily), but still 2 results. What should I be doing to get what I want out of this query? Note that I need to get the fetch mode specified in the query, not in the entity

Problem with @Basic(fetch = FetchType.LAZY)

I have a class where two fields are annotated with @Basic(fetch = FetchType.LAZY ... app). Yet they don't seem to be fetched lazily. This class should hopefully demonstrate the problem ... ; @Basic(fetch = FetchType.LAZY) private String description; @Basic(fetch = FetchType.LAZY

Retrieving JPA Entity Objects

Eager Fetch Retrieval of an entity object from the database might cause automatic retrieval ... retrieval by using a lazy fetch type: @Entity class Employee { : @ManyToOne(fetch=FetchType ... with the FetchType.LAZY fetch policy is initialized to reference a new managed hollow object (unless

[ODB1] Chapter 4 - JDO Metadata

="transactional" /> <field name="f3" default-fetch-group="true" /> <field name="f4" default-fetch-group="false" /> <field name="f5" embedded="true" /> <field name="f6 ... to its value at the beginning of the transaction. default-fetch-group (true | false) The default-fetch


. The flags for detachment (DETACH_LOAD_FIELDS and DETACH_UNLOAD_FIELDS) and the active fetch groups determine the scope of fetching for the graph of instances reachable from the pc parameter. The state ... _FIELDS) and the active fetch groups determine the scope of fetching for the graph of instances

Getting Started

ObjectDB is very easy to use. Follow the Getting Started Tutorial and the Quick Tour manual chapter and in minutes you may be able to write and run first Java programs against ObjectDB.

Prior knowledge or experience in database programming (SQL, JDBC, ORM, JPA, etc.) is not required, but some background in using the Java language is essential.

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