![]() Transaction and coordinates the writing out of changesĪnd the resolution of concurrency problems. a list of objects affected by a business A unit of work is aĭesign pattern described by Martin Fowler as Should you open and close a Session and how do you demarcate theĭatabase transaction boundaries? These questions are addressed in the following sections.įirst, let's define a unit of work. Span several database transactions, or is this a one-to-one relationship of scopes? When What is the scope of a unit of work? Can a single Hibernate Session It is not recommended that you hold aĭatabase transaction open during user think time until the unit of work is Long database transactions will prevent your application from scaling In order to reduce lock contention in the database, a database transaction has to be as short as possible. Used once and then discarded for: a single request, a conversation or a single unit of work.Ī Session will not obtain a JDBC Connection, It is created once, usually onĪpplication startup, from a Configuration instance.Ī Session is an inexpensive, non-threadsafe object that should be Intended to be shared by all application threads. Session, as well as database transactions and long conversations.Ī SessionFactory is an expensive-to-create, threadsafe object, The discussion of concurrency control in Hibernate begins with the granularity of This API are discussed later in this chapter. SELECT FOR UPDATE syntax, a (minor) API for pessimistic locking of rows. In addition to versioning for automatic optimistic concurrency control, Hibernate also Reporting queries that return scalar values. Provides repeatable reads for lookup by identifier and entity queries and not Session, which is also a transaction-scoped cache, Hibernate Your application can expect the behavior asĭefined by the isolation level of your database transactions. Hibernate does not lock objects in memory. ![]() JDBC, ANSI, and transaction isolation specification of your database management system. It is recommended that you spend some time with the Hibernate directly uses JDBC connections and JTA resources withoutĪdding any additional locking behavior. The most important point about Hibernate and concurrency control is that it isĮasy to understand. Detached objects and automatic versioning 12.3.4. Extended session and automatic versioning 12.3.3.
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