Hibernate.orgCommunity Documentation
As an ORM tool, probably the single most important thing you need to tell Hibernate is how to connect to
your database so that it may connect on behalf of your application. This is ultimately the function of
the org.hibernate.engine.jdbc.connections.spi.ConnectionProvider
interface. Hibernate provides some out of the box implementations of this interface. ConnectionProvider
is also an extension point, so you can also use custom implementations from third parties or written yourself.
The ConnectionProvider to use is defined by the hibernate.connection.provider_class setting.
See the org.hibernate.cfg.AvailableSettings#CONNECTION_PROVIDER
Generally speaking applications should not have to configure a ConnectionProvider explicitly if using one of the Hibernate-provided implementations. Hibernate will internally determine which ConnectionProvider to use based on the following algorithm:
If hibernate.connection.provider_class is set, it takes precedence
else if hibernate.connection.datasource is set -> Section 6.1.1, “Using DataSources”
else if any setting prefixed by hibernate.c3p0. is set -> Section 6.1.2, “Using c3p0”
else if any setting prefixed by hibernate.proxool. is set -> Section 6.1.3, “Using Proxool”
else if any setting prefixed by hibernate.hikari. is set -> Section 6.1.4, “Using Hikari”
else if hibernate.connection.url is set -> Section 6.1.5, “Using Hibernate's built-in (and unsupported) pooling”
Hibernate can integrate with a javax.sql.DataSource for obtaining
JDBC Connections. Applications would tell Hibernate about the DataSource via the (required)
hibernate.connection.datasource setting which can either specify a JNDI name
or would reference the actual DataSource instance. For cases where a JNDI name is given, be sure
to read Chapter 8, JNDI
For JPA applications, note that hibernate.connection.datasource corresponds to
either javax.persistence.jtaDataSource or javax.persistence.nonJtaDataSource.
The DataSource ConnectionProvider also (optionally) accepts the hibernate.connection.username
and hibernate.connection.password. If specified, the form of DataSource#getConnection
accepting username and password will be used. Otherwise the no-arg form is used.
To use this integration, the application must include the hibernate-c3p0 module jar (as well as its dependencies) on the classpath.
Hibernate also provides support for applications to use c3p0 connection pooling. When using this c3p0 support, a number of additional configuration settings are recognized.
Transaction isolation of the Connections is managed by the ConnectionProvider itself. See Section 6.1.7, “ConnectionProvider support for transaction isolation setting”.
Additional settings
hibernate.connection.driver_classThe name of the JDBC Driver class to use
hibernate.connection.urlThe JDBC connection url.
hibernate.connection. (other than the "special ones")
These all have the hibernate.connection. prefix stripped and the
rest will be passed as JDBC connection properties
hibernate.c3p0.min_size or c3p0.minPoolSizeThe minimum size of the c3p0 pool. See http://www.mchange.com/projects/c3p0/#minPoolSize
hibernate.c3p0.max_size or c3p0.maxPoolSizeThe maximum size of the c3p0 pool. See http://www.mchange.com/projects/c3p0/#maxPoolSize
hibernate.c3p0.timeout or c3p0.maxIdleTimeThe Connection idle time. See http://www.mchange.com/projects/c3p0/#maxIdleTime
hibernate.c3p0.max_statements or c3p0.maxStatementsControls the c3p0 PreparedStatement cache size (if using). See http://www.mchange.com/projects/c3p0/#maxStatements
hibernate.c3p0.acquire_increment or c3p0.acquireIncrementNumber of connections c3p0 should acquire at a time when pool is exhauted. See http://www.mchange.com/projects/c3p0/#acquireIncrement
hibernate.c3p0.idle_test_period or c3p0.idleConnectionTestPeriodIdle time before a c3p0 pooled connection is validated. See http://www.mchange.com/projects/c3p0/#idleConnectionTestPeriod
c3p0.initialPoolSizeThe initial c3p0 pool size. If not specified, default is to use the min pool size. See http://www.mchange.com/projects/c3p0/#initialPoolSize
hibernate.c3p0.
Will have the hibernate. portion stripped and be passed to c3p0.
c3p0.Get passed to c3p0 as is. See http://www.mchange.com/projects/c3p0/#configuration
To use this integration, the application must include the hibernate-proxool module jar (as well as its dependencies) on the classpath.
Hibernate also provides support for applications to use Proxool connection pooling.
Transaction isolation of the Connections is managed by the ConnectionProvider itself. See Section 6.1.7, “ConnectionProvider support for transaction isolation setting”.
The hibernate.proxool.xml setting names a Proxool configuration XML
file to be loaded as a classpath resource and loaded by Proxool's JAXPConfigurator.
See http://proxool.sourceforge.net/configure.html.
hibernate.proxool.pool_alias must be set to indicate which pool to use.
The hibernate.proxool.properties setting names a Proxool configuration Properties
file to be loaded as a classpath resource and loaded by Proxool's PropertyConfigurator.
See http://proxool.sourceforge.net/configure.html.
hibernate.proxool.pool_alias must be set to indicate which pool to use.
To use this integration, the application must include the hibernate-hikari module jar (as well as its dependencies) on the classpath.
Hibernate also provides support for applications to use Hikari connection pool.
Set all of your Hikari settings in Hibernate prefixed by hibernate.hikari.
and this ConnectionProvider will pick them up and pass them along to Hikari. Additionally, this
ConnectionProvider will pick up the following Hibernate-specific properties and map
them to the corresponding Hikari ones (any hibernate.hikari. prefixed ones have precedence):
Hibernate-specific properties recognized by Hikari ConnectionProvider
hibernate.connection.driver_classMapped to Hikari's driverClassName setting
hibernate.connection.urlMapped to Hikari's jdbcUrl setting
hibernate.connection.usernameMapped to Hikari's username setting
hibernate.connection.passwordMapped to Hikari's password setting
hibernate.connection.isolation
Mapped to Hikari's transactionIsolation setting. See
Section 6.1.7, “ConnectionProvider support for transaction isolation setting”. Note that
Hikari only supports JDBC standard isolation levels (apparently).
hibernate.connection.autocommitMapped to Hikari's autoCommit setting
It is possible to use Hibernate by simply passing a Connection to use to the Session when the Session is opened. This usage is discouraged and not discussed here.
All of the provided ConnectionProvider implementations, other than DataSourceConnectionProvider,
support consistent setting of transaction isolation for all Connections obtained from the underlying
pool. The value for hibernate.connection.isolation can be specified in
one of 3 formats:
the integer value accepted at the JDBC level
the name of the java.sql.Connection constant field
representing the isolation you would like to use. For example,
TRANSACTION_REPEATABLE_READ for
java.sql.Connection#TRANSACTION_REPEATABLE_READ. Not that this is
only supported for JDBC standard isolations, not for isolation levels specific to
a particular JDBC driver.
a short-name version of the java.sql.Connection constant field
without the TRANSACTION_ prefix. For example,
REPEATABLE_READ for
java.sql.Connection#TRANSACTION_REPEATABLE_READ. Again, this is
only supported for JDBC standard isolations, not for isolation levels specific to
a particular JDBC driver.
Although SQL is relatively standardized, each database vendor uses a subset and superset of
ANSI SQL defined syntax. This is referred to as the database's dialect.
Hibernate handles variations across these dialects through its
org.hibernate.dialect.Dialect class and the various subclasses for each database
vendor.
In most cases Hibernate will be able to determine the proper Dialect to use by asking some questions of the JDBC Connection during bootstrap. For information on Hibernate's ability to determine the proper Dialect to use (and your ability to influence that resolution), see Section 20.3, “Dialect resolution”
If for some reason it is not able to determine the proper one
or you want to use a custom Dialect, you will need to set the hibernate.dialect setting.