With JDBC, a database is represented by a URL (Uniform Resource Locator). With PostgreSQL™, this takes one of the following forms:
The parameters have the following meanings:
The host name of the server. Defaults to
localhost. To specify an IPv6
address your must enclose the
host parameter with square brackets, for
The port number the server is listening on. Defaults to the PostgreSQL™ standard port number (5432).
The database name.
To connect, you need to get a
Connection instance from JDBC. To do this, you use
Connection db = DriverManager.getConnection(url, username, password);
In addition to the standard connection parameters the driver supports a number
of additional properties which can be used to specify additional driver behaviour
specific to PostgreSQL™. These properties may be specified in either the connection
URL or an additional
Properties object parameter to
The following examples illustrate the use of both methods to establish a SSL
String url = "jdbc:postgresql://localhost/test";
Properties props = new Properties();
Connection conn = DriverManager.getConnection(url, props);
String url = "jdbc:postgresql://localhost/test?user=fred&password=secret&ssl=true";
Connection conn = DriverManager.getConnection(url);
user = String
The database user on whose behalf the connection is being made.
password = String
The database user's password.
Connect using SSL. The driver must have been compiled with SSL support. This property does not need a value associated with it. The mere presence of it specifies a SSL connection. However, for compatibility with future versions, the value "true" is preferred. For more information see Chapter 4, Using SSL.
sslfactory = String
The provided value is a class name to use as the
establishing a SSL connection. For more information see the section
called “Custom SSLSocketFactory”.
sslfactoryarg = String
This value is an optional argument to the constructor of the sslfactory class provided above. For more information see the section called “Custom SSLSocketFactory”.
compatible = String
Act like an older version of the driver to retain compatibility with older
applications. At the moment this controls two driver behaviours: the
handling of binary data fields, and the handling of parameters set via
Older versions of the driver used this property to also control the
protocol used to connect to the backend. This is now controlled by the
Information on binary data handling is detailed in Chapter 7, Storing Binary Data. To force the use of Large Objects set the compatible property to 7.1.
compatible is set to 7.4 or below, the default for the
parameter is changed to
sendBufferSize = int
Sets SO_SNDBUF on the connection stream
recvBufferSize = int
Sets SO_RCVBUF on the connection stream
protocolVersion = String
The driver supports both the V2 and V3 frontend/backend protocols. The V3 protocol was introduced in 7.4 and the driver will by default try to connect using the V3 protocol, if that fails it will fall back to the V2 protocol. If the protocolVersion property is specified, the driver will try only the specified protocol (which should be either "2" or "3"). Setting protocolVersion to "2" may be used to avoid the failed attempt to use the V3 protocol when connecting to a version 7.3 or earlier server, or to force the driver to use the V2 protocol despite connecting to a 7.4 or greater server.
loglevel = int
Set the amount of logging information printed to the DriverManager's
current value for LogStream or LogWriter. It currently supports values
org.postgresql.Driver.DEBUG (2) and
INFO will log very little information while
DEBUG will produce significant
detail. This property is only really useful if you are a developer or
are having problems with the driver.
charSet = String
The character set to use for data sent to the database or received from the database. This property is only relevant for server versions less than or equal to 7.2. The 7.3 release was the first with multibyte support compiled by default and the driver uses its character set translation facilities instead of trying to do it itself.
allowEncodingChanges = boolean
When using the V3 protocol the driver monitors changes in certain server
configuration parameters that should not be touched by end users. The
client_encoding setting is set by the driver and should not be altered.
If the driver detects a change it will abort the connection. There is
one legitimate exception to this behaviour though, using the
on a file residing on the server's filesystem. The only means of specifying
the encoding of this file is by altering the
The JDBC team considers this a failing of the
COPY command and hopes to
provide an alternate means of specifying the encoding in the future, but
for now there is this URL parameter. Enable this only if you need to
override the client encoding when doing a copy.
logUnclosedConnections = boolean
Clients may leak
Connection objects by failing to call its
method. Eventually these objects will be garbage collected and the
finalize() method will be called which will close the
caller has neglected to do this himself. The usage of a finalizer is just
a stopgap solution. To help developers detect and correct the source of
these leaks the
logUnclosedConnections URL parameter has been added.
It captures a stacktrace at each
Connection opening and if the
method is reached without having been closed the stacktrace is printed
to the log.
prepareThreshold = int
Determine the number of
PreparedStatement executions required before
switching over to use server side prepared statements. The default is
five, meaning start using server side prepared statements on the fifth
execution of the same
PreparedStatement object. More information on
server side prepared statements is available in the section called
“Server Prepared Statements”.
loginTimeout = int
Specify how long to wait for establishment of a database connection. The timeout is specified in seconds.
socketTimeout = int
The timeout value used for socket read operations. If reading from the server takes longer than this value, the connection is closed. This can be used as both a brute force global query timeout and a method of detecting network problems. The timeout is specified in seconds and a value of zero means that it is disabled.
tcpKeepAlive = boolean
Enable or disable TCP keep-alive probe. The default is
unknownLength = int
Certain postgresql types such as
TEXT do not have a well defined length.
When returning meta-data about these types through functions like
we must provide a value and various client tools have different ideas
about what they would like to see. This parameter specifies the length
to return for types of unknown length.
stringtype = String
Specify the type to use when binding
PreparedStatement parameters set
stringtype is set to
VARCHAR (the default), such
parameters will be sent to the server as varchar parameters. If
is set to
unspecified, parameters will be sent to the server as untyped
values, and the server will attempt to infer an appropriate type. This
is useful if you have an existing application that uses
set parameters that are actually some other type, such as integers, and
you are unable to change the application to use an appropriate method
kerberosServerName = String
The Kerberos service name to use when authenticating with GSSAPI. This is equivalent to libpq's PGKRBSRVNAME environment variable and defaults to "postgres".
jaasApplicationName = String
Specifies the name of the JAAS system or application login configuration.