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Reorder properties. There is no "correct" order.

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Brett Wooldridge 11 years ago
parent 0fa08d0011
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README.md
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@ -62,6 +62,21 @@ comes with *sane* defaults that let a great many deployments run without any add
This property controls the default auto-commit behavior of connections returned from the pool.
It is a boolean value. *Default: true*
:negative_squared_cross_mark:``readOnly``<br/>
This property controls whether *Connections* obtained from the pool are in read-only mode by
default. Note some databases do not support the concept of read-only mode, while others provide
query optimizations when the *Connection* is set to read-only. Whether you need this property
or not will depend largely on your application and database. *Default: false*
:abc:``transactionIsolation``<br/>
This property controls the default transaction isolation level of connections returned from
the pool. If this property is not specified, the default transaction isolation level defined
by the JDBC driver is used. Typically, the JDBC driver default transaction isolation level
should be used. Only use this property if you have specific isolation requirements that are
common for all queries, otherwise simply set the isolation level manually when creating or
preparing statements. The value of this property is the constant name from the ``Connection``
class such as ``TRANSACTION_READ_COMMITTED``, ``TRANSACTION_REPEATABLE_READ``, etc. *Default: none*
:abc:``catalog``<br/>
This property sets the default *catalog* for databases that support the concept of catalogs.
If this property is not specified, the default catalog defined by the JDBC driver is used.
@ -72,41 +87,11 @@ This property sets a SQL statement that will be executed after every new connect
before adding it to the pool. If this SQL is not valid or throws an exception, it will be
treated as a connection failure and the standard retry logic will be followed. *Default: none*
:abc:``connectionTestQuery``<br/>
This is for "legacy" databases that do not support the JDBC4 Connection.isValid() API. This
is the query that will be executed just before a connection is given to you from the pool to
validate that the connection to the database is still alive. It is database dependent and
should be a query that takes very little processing by the database (eg. "VALUES 1"). **See
the ``jdbc4ConnectionTest`` property for a more efficent alive test.** One of either this
property or ``jdbc4ConnectionTest`` must be specified. *Default: none*
:watch:``connectionTimeout``<br/>
This property controls the maximum number of milliseconds that a client (that's you) will wait
for a connection from the pool. If this time is exceeded without a connection becoming
available, a SQLException will be thrown. *Default: 30000 (30 seconds)*
:arrow_right:``dataSource``<br/>
This property is only available via programmatic configuration. This property allows you
to directly set the instance of the ``DataSource`` to be wrapped by the pool, rather than
having HikariCP construct it via reflection. When this property is specified, the
``dataSourceClassName`` property and all DataSource-specific properties will be ignored.
*Default: none*
:abc:``dataSourceClassName``<br/>
This is the name of the ``DataSource`` class provided by the JDBC driver. Consult the
documentation for your specific JDBC driver to get this class name, or see the [table](https://github.com/brettwooldridge/HikariCP#popular-datasource-class-names) below.
Note XA data sources are not supported. XA requires a real transaction manager like
[bitronix](https://github.com/bitronix/btm). Note that you do not need this property if you are using
``driverClassName`` to wrap an old-school DriverManager-based JDBC driver. The HikariCP team
considers ``dataSourceClassName`` to be a superior method of creating connections compared to
``driverClassName``. *Default: none*
:abc:``driverClassName``<br/>
This property allows HikariCP to wrap an old-school JDBC driver as a ``javax.sql.DataSource``.
It is unnecessary when using the ``dataSourceClassName`` property, which is the preferred way
of creating connections in HikariCP. DataSources are provided by all but the oldest JDBC drivers.
If ``driverClassName`` is used, then the ``jdbcUrl`` property must also be set. *Default: none*
:watch:``idleTimeout``<br/>
This property controls the maximum amount of time (in milliseconds) that a connection is
allowed to sit idle in the pool. Whether a connection is retired as idle or not is subject
@ -114,24 +99,65 @@ to a maximum variation of +30 seconds, and average variation of +15 seconds. A
will never be retired as idle *before* this timeout. A value of 0 means that idle connections
are never removed from the pool. *Default: 600000 (10 minutes)*
:watch:``maxLifetime``<br/>
This property controls the maximum lifetime of a connection in the pool. When a connection
reaches this timeout, even if recently used, it will be retired from the pool. An in-use
connection will never be retired, only when it is idle will it be removed. We strongly
recommend setting this value, and using something reasonable like 30 minutes or 1 hour. A
value of 0 indicates no maximum lifetime (infinite lifetime), subject of course to the
``idleTimeout`` setting. *Default: 1800000 (30 minutes)*
:watch:``leakDetectionThreshold``<br/>
This property controls the amount of time that a connection can be out of the pool before a
message is logged indicating a possible connection leak. A value of 0 means leak detection
is disabled. While the default is 0, and other connection pool implementations state that
leak detection is "not for production" as it imposes a high overhead, at least in the case
of HikariCP the imposed overhead is only 5μs (*microseconds*) split between getConnection()
and close(). Maybe other pools are doing it wrong, but feel free to use leak detection under
HikariCP in production environments if you wish. *Default: 0*
:negative_squared_cross_mark:``initializationFailFast``<br/>
This property controls whether the pool will "fail fast" if the pool cannot be seeded with
initial connections successfully. If connections cannot be created at pool startup time,
a ``RuntimeException`` will be thrown from the ``HikariDataSource`` constructor. This
property has no effect if ``minimumPoolSize`` is 0. *Default: false*
:negative_squared_cross_mark:``isolateInternalQueries``<br/>
This property determines whether HikariCP isolates internal pool queries, such as the
connection alive test, in their own transaction. Since these are typically read-only
queries, it is rarely necessary to encapsulate them in their own transaction. This
property only applies if ``autoCommit`` is disabled. *Default: false*
:white_check_mark:``jdbc4ConnectionTest``<br/>
This property is a boolean value that determines whether the JDBC4 Connection.isValid() method
is used to check that a connection is still alive. This value is mutually exclusive with the
``connectionTestQuery`` property, and this method of testing connection validity should be
preferred if supported by the JDBC driver. *Default: true*
:abc:``connectionTestQuery``<br/>
This is for "legacy" databases that do not support the JDBC4 Connection.isValid() API. This
is the query that will be executed just before a connection is given to you from the pool to
validate that the connection to the database is still alive. It is database dependent and
should be a query that takes very little processing by the database (eg. "VALUES 1"). **See
the ``jdbc4ConnectionTest`` property for a more efficent alive test.** One of either this
property or ``jdbc4ConnectionTest`` must be specified. *Default: none*
:abc:``dataSourceClassName``<br/>
This is the name of the ``DataSource`` class provided by the JDBC driver. Consult the
documentation for your specific JDBC driver to get this class name, or see the [table](https://github.com/brettwooldridge/HikariCP#popular-datasource-class-names) below.
Note XA data sources are not supported. XA requires a real transaction manager like
[bitronix](https://github.com/bitronix/btm). Note that you do not need this property if you are using
``driverClassName`` to wrap an old-school DriverManager-based JDBC driver. The HikariCP team
considers ``dataSourceClassName`` to be a superior method of creating connections compared to
``driverClassName``. *Default: none*
:abc:``driverClassName``<br/>
This property allows HikariCP to wrap an old-school JDBC driver as a ``javax.sql.DataSource``.
It is unnecessary when using the ``dataSourceClassName`` property, which is the preferred way
of creating connections in HikariCP. DataSources are provided by all but the oldest JDBC drivers.
If ``driverClassName`` is used, then the ``jdbcUrl`` property must also be set. *Default: none*
:arrow_right:``dataSource``<br/>
This property is only available via programmatic configuration. This property allows you
to directly set the instance of the ``DataSource`` to be wrapped by the pool, rather than
having HikariCP construct it via reflection. When this property is specified, the
``dataSourceClassName`` property and all DataSource-specific properties will be ignored.
*Default: none*
:abc:``jdbcUrl``<br/>
This property is only used when the ``driverClassName`` property is used to wrap an old-school
JDBC driver as a ``javax.sql.DataSource``. While JBDC URLs are popular, HikariCP does not
@ -142,22 +168,12 @@ using the more modern and maintainable ``dataSourceClassName`` approach instead.
this property is used, you may still use *DataSource* properties to configure your driver and
is in fact recommended. *Default: none*
:watch:``leakDetectionThreshold``<br/>
This property controls the amount of time that a connection can be out of the pool before a
message is logged indicating a possible connection leak. A value of 0 means leak detection
is disabled. While the default is 0, and other connection pool implementations state that
leak detection is "not for production" as it imposes a high overhead, at least in the case
of HikariCP the imposed overhead is only 5μs (*microseconds*) split between getConnection()
and close(). Maybe other pools are doing it wrong, but feel free to use leak detection under
HikariCP in production environments if you wish. *Default: 0*
:watch:``maxLifetime``<br/>
This property controls the maximum lifetime of a connection in the pool. When a connection
reaches this timeout, even if recently used, it will be retired from the pool. An in-use
connection will never be retired, only when it is idle will it be removed. We strongly
recommend setting this value, and using something reasonable like 30 minutes or 1 hour. A
value of 0 indicates no maximum lifetime (infinite lifetime), subject of course to the
``idleTimeout`` setting. *Default: 1800000 (30 minutes)*
:hash:``minimumIdle``<br/>
This property controls the minimum number of *idle connections* that HikariCP tries to maintain
in the pool. If the idle connections dip below this value, HikariCP will make a best effort to
add additional connections quickly and efficiently. However, for maximum performance and
responsiveness to spike demands, we recommend *not* setting this value and instead allowing
HikariCP to act as a *fixed size* connection pool. *Default: same as maximumPoolSize*
:hash:``maximumPoolSize``<br/>
This property controls the maximum size that the pool is allowed to reach, including both
@ -167,12 +183,9 @@ by your execution environment. When the pool reaches this size, and no idle con
available, calls to getConnection() will block for up to ``connectionTimeout`` milliseconds
before timing out. *Default: 10*
:hash:``minimumIdle``<br/>
This property controls the minimum number of *idle connections* that HikariCP tries to maintain
in the pool. If the idle connections dip below this value, HikariCP will make a best effort to
add additional connections quickly and efficiently. However, for maximum performance and
responsiveness to spike demands, we recommend *not* setting this value and instead allowing
HikariCP to act as a *fixed size* connection pool. *Default: same as maximumPoolSize*
:abc:``username``<br/>
This property sets the default authentication username used when obtaining *Connections* from
the underlying driver. *Default: none*
:abc:``password``<br/>
This property sets the default authentication password used when obtaining *Connections* from
@ -182,28 +195,15 @@ the underlying driver. *Default: none*
This property represents a user-defined name for the connection pool and appears mainly
in a JMX management console to identify pools and pool configurations. *Default: auto-generated*
:negative_squared_cross_mark:``readOnly``<br/>
This property controls whether *Connections* obtained from the pool are in read-only mode by
default. Note some databases do not support the concept of read-only mode, while others provide
query optimizations when the *Connection* is set to read-only. Whether you need this property
or not will depend largely on your application and database. *Default: false*
:negative_squared_cross_mark:``registerMbeans``<br/>
This property controls whether or not JMX Management Beans ("MBeans") are registered or not.
*Default: false*
:abc:``transactionIsolation``<br/>
This property controls the default transaction isolation level of connections returned from
the pool. If this property is not specified, the default transaction isolation level defined
by the JDBC driver is used. Typically, the JDBC driver default transaction isolation level
should be used. Only use this property if you have specific isolation requirements that are
common for all queries, otherwise simply set the isolation level manually when creating or
preparing statements. The value of this property is the constant name from the ``Connection``
class such as ``TRANSACTION_READ_COMMITTED``, ``TRANSACTION_REPEATABLE_READ``, etc. *Default: none*
:abc:``username``<br/>
This property sets the default authentication username used when obtaining *Connections* from
the underlying driver. *Default: none*
:negative_squared_cross_mark:``isolateInternalQueries``<br/>
This property determines whether HikariCP isolates internal pool queries, such as the
connection alive test, in their own transaction. Since these are typically read-only
queries, it is rarely necessary to encapsulate them in their own transaction. This
property only applies if ``autoCommit`` is disabled. *Default: false*
***Missing Knobs***<br/>
HikariCP has plenty of "knobs" to turn as you can see above, but comparatively less than some other pools.

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