Logging using java.util.logging
The PostgreSQL JDBC Driver supports the use of logging (or tracing) to help resolve issues with the pgJDBC Driver when is used in your application.
The pgJDBC Driver uses the logging APIs of
java.util.logging that is part of Java since JDK 1.4, which makes it a good choice for the driver since it doesn’t add any external dependency for a logging framework.
java.util.logging is a very rich and powerful tool, it’s beyond the scope of these docs to explain how to use it to it’s full potential, for that please refer to Java Logging Overview.
This logging support was added since version 42.0.0 of the pgJDBC Driver, and previous versions uses a custom mechanism to enable logging that it is replaced by the use of
java.util.logging in current versions, the old mechanism is no longer available.
Please note that while most people asked the use of a Logging Framework for a long time, this support is mainly to debug the driver itself and not for general sql query debug.
The Logging APIs offer both static and dynamic configuration control. Static control enables field service staff to set up a particular configuration and then re-launch the application with the new logging settings. Dynamic control allows for updates to the logging configuration within a currently running program.
The root logger used by the pgJDBC driver is
The default Java logging framework stores its configuration in a file called
logging.properties . Settings are stored per line using a dot notation format. Java installs a global configuration file in the
lib folder of the Java installation directory, although you can use a separate configuration file by specifying the
java.util.logging.config.file property when starting a Java program.
logging.properties files can also be created and stored with individual projects.
The following is an example of setting that you can make in the
# Specify the handler, the handlers will be installed during VM startup. handlers = java.util.logging.FileHandler # Default global logging level. .level = OFF # Default file output is in user's home directory. java.util.logging.FileHandler.pattern = %h/pgjdbc%u.log java.util.logging.FileHandler.limit = 5000000 java.util.logging.FileHandler.count = 20 java.util.logging.FileHandler.formatter = java.util.logging.SimpleFormatter java.util.logging.FileHandler.level = FINEST java.util.logging.SimpleFormatter.format = %1$tY-%1$tm-%1$td %1$tH:%1$tM:%1$tS %4$s %2$s %5$s%6$s%n # Facility specific properties. org.postgresql.level = FINEST
And when you run your application you pass the system property:
java -jar -Djava.util.logging.config.file=logging.properties run.jar