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General Performance Issues Illustrated with a Specific Method

.address" type="java.lang.String" /> </ObjectResultBuilder> </newQueryResponse> ="0.00/0.00" variable ... " future="true"> <btreePlan complexity="12.4799" eval="3.70/6.30" variable="v$1(Person)" scope="index(-116[all])" /> <btreePlan complexity="12.5432" eval="3.72/6.30" variable="v$1(Person)" scope="index

OutOfMemoryError in a query with many variables

of a query. Can you post the query? Does it have a large number of variables (> 20) ? support Support Hi ... doesn't handle well queries with a lot of variables, and complex navigation (e.g. $1.postalAddresses.deliveryPoint.deliveryPointLocation.thoroughfare.name) generates many variables


instances: DELETE FROM Country       // no variable DELETE FROM Country c     // an optional variable DELETE FROM Country AS c  // AS + an optional variable ObjectDB supports using the java.lang ... multiple variables and JOIN, and cannot include the GROUP BY, HAVING and ORDER BY clauses


/ 10 The UPDATE clause defines exactly one range variable (with or without an explicit variable name) for iteration. Multiple variables and JOIN are not supported. The SET clause defines one or more field update expressions (using the range variable name - if defined). Multiple field update

ORDER BY clause (JPQL / Criteria API)

Alias variables are referred to as result variables to distinguish them from the identification variables that are defined in the FROM clause. Order Direction (ASC, DESC) The default ordering direction ... "))); Unlike other methods for setting criteria query clauses - the orderBy method takes a variable number

GROUP BY and HAVING clauses

. Only identification variables and path expressions are currently supported in the GROUP BY clause by ... takes a variable number of arguments specifying one or more grouping expressions (or a list ... an Expression<Boolean> argument and the other having form takes a variable number of Predicate arguments

SELECT clause (JPQL / Criteria API)

can be added to the SELECT clause by using a bound JOIN variable in the FROM clause. Nested path expressions ... - multiselect, which takes a variable number of arguments representing multiple selections, and builds

JPA Persistable Types

no-arg constructor. cannot be final and cannot have final methods or final instance variables. ObjectDB ... are forbidden). Instance (non static) variables cannot be final, but classes and methods can be final

JPA Criteria API Queries

the built query. Then a Root instance is created to define a range variable in the FROM clause. Finally, the range variable, c, is also used in the SELECT clause as the query result expression


of instances, and the filter. There are optional elements: parameter declarations, variable declarations ... variables of a method setFilter and setOrdering correspond to the method body ... , variables and parameters. The method setClass introduces the name of the candidate class in the type

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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