JPA Persistence Guide (v5.2) Table of Contents EntityManagerFactory. 2 Create an EMF in JavaSE . 2 Create an EMF in JavaEE . 2 Persistence Unit . 3 EntityManagerFactory Properties . 6 Closing EntityManagerFactory . 27 Level 2 Cache. 27 Datastore Schema. 34 Schema Generation for persistence-unit . 34 Schema Auto-Generation at runtime . 35 Schema Generation : Validation . 36 Schema Generation : Naming Issues . 36 Schema Generation : Column Ordering . 37 Schema : Read-Only. 37 SchemaTool . 38 Schema Adaption . 44 RDBMS : Datastore Schema SPI . 44 EntityManager. 48 Opening/Closing an EntityManager. 48 Persisting an Object. 49 Persisting multiple Objects in one call . 49 Finding an object by its identity . 50 Finding an object by its class and unique key field value(s) . 50 Deleting an Object . 51 Deleting multiple Objects. 51 Modifying a persisted Object. 52 Modifying multiple persisted Objects . 52 Refreshing a persisted Object . 52 Getting EntityManager for an object. 53 Cascading Operations . 53 Orphans . 54 Managing Relationships . 54 Level 1 Cache. 56 Object Lifecycle. 58 Transaction PersistenceContext . 58 Extended PersistenceContext . 58 Detachment . 58 Helper Methods . 59 Transactions . 60 Locally-Managed Transactions. 60 JTA Transactions. 61 Container-Managed Transactions . 63 Spring-Managed Transactions . 63 No Transactions . 63 Transaction Isolation . 64 Read-Only Transactions . 64 Flushing . 65 Transactions with lots of data. 66 Transaction Savepoints . 67 Locking . 68 Optimistic Locking. 68 Pessimistic (Datastore) Locking . 69 Datastore.