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Low performance when getting grove roots

Hi, I have a grove-like structure of objects, every objects referencing its parent. Root objects have null as the value of this parent reference. To find the roots I execute a query. If the number of objects in the tree is significant, this query takes almost forever, it seems ObjectDB loads


javax.persistence.criteria Interface Root<X> Superinterfaces: Expression<X>, FetchParent<X,X>, From<X,X>, Path<X>, Selection<X>, TupleElement<X> A root type in the from clause. Query roots always reference entities. Since: JPA 2.0 Learn how to use JPA criteria API's Root in Chapter 4


Method javax.persistence.criteria.Root EntityType<X> getModel() Return the metamodel entity corresponding to the root. Returns: metamodel entity corresponding to the root Since: JPA 2.0

Criteria Query From Elements

(bound by an entity class) are represented by the Root subinterface: Join variables (bound by

FROM clause (JPQL / Criteria API)

to have a single range variable that serves as a root and additional join variables that are bound to path ... are represented by the Root interface. Join variables are represented by the Join interface (and its sub interfaces). Criteria Query Roots The CriteriaQuery's from method serves as a factory of Root instances

Paths and Types in JPQL and Criteria API

are represented in the JPA Criteria API by the Path interface and by its subinterfaces (From, Root, Join and Join's descendants). Path Expressions The Root and Join interfaces (which are subinterfaces ... or property), can be constructed by the get method: // FROM Variable Paths: Root<Country

SELECT clause (JPQL / Criteria API)

<Country> q = cb.createQuery(Country.class); Root<Country> c = q.from(Country.class); q.select(c ... : CriteriaQuery<Object[]> q = cb.createQuery(Object[].class); Root<Country> c = q.from(Country.class); q ... as a clean alternative to Object[]: CriteriaQuery<Tuple> q = cb.createTupleQuery(); Root


Method javax.jdo.FetchPlan FetchPlan setDetachmentRoots( Collection roots ) Set the roots for DetachAllOnCommit. Parameters: roots - Collection of the detachment roots. Since: JDO 2.0

[ODB1] Chapter 9 - ObjectDB Explorer

information about the database and the bottom sub window displays a list of root objects that the database contains (root objects are discussed in chapter 6). The "Query" window enables a user to execute JDOQL ... all the instances of that class. Select a root object in the "Database" tabbed window to view the content

[ODB1] Chapter 6 - Persistent Objects

. Objects with names are called root objects in object databases, because navigation in the database ... directly by using its object ID. A root object can also be retrieved by its name. It is also possible ... A root object, which is a database object with an assigned name, can be retrieved by using its name

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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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