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From Eclipsepedia

Contents 1 How to Optimize Object Graph Loading with JPA 1.1 Example Model 1.2 Querying without Optimizations 1.3 JPQL JOIN FETCH 1.4 EclipseLink Hints 1.4.1 JOIN FETCH Hint 1.4.2 BATCH Hint

How to Optimize Object Graph Loading with JPA

A common problem developers face when using object-relational solutions is how to optimize the loading of a graph or related objects. By default a query for the root object type and default navigation through the graph can result in a N+1 SQL performance problem. This how-to highlights EclipseLink JPA's available solutions.

Example Model

Querying without Optimizations

JPQL JOIN FETCH

EclipseLink Hints

EclipseLink provides additional support for joining and batch reading using query hints.

JOIN FETCH Hint

BATCH Hint