3.5. Logging

Hibernate logs various events using Apache commons-logging.
The commons-logging service will direct output to either Apache Log4j (if you include log4j.jar in your classpath) or JDK1.4 logging (if running under JDK1.4 or above). You may download Log4j from http://jakarta.apache.org. To use Log4j you will need to place a log4j.properties file in your classpath, an example properties file is distributed with Hibernate in the src/ directory.
We strongly recommend that you familiarize yourself with Hibernate's log messages. A lot of work has been put into making the Hibernate log as detailed as possible, without making it unreadable. It is an essential troubleshooting device. The most interesting log categories are the following:

Table 3.9. Hibernate Log Categories

Category Function
org.hibernate.SQL Log all SQL DML statements as they are executed
org.hibernate.type Log all JDBC parameters
org.hibernate.tool.hbm2ddl Log all SQL DDL statements as they are executed
org.hibernate.pretty Log the state of all entities (max 20 entities) associated with the session at flush time
org.hibernate.cache Log all second-level cache activity
org.hibernate.transaction Log transaction related activity
org.hibernate.jdbc Log all JDBC resource acquisition
org.hibernate.hql.ast.AST Log HQL and SQL ASTs during query parsing
org.hibernate.secure Log all JAAS authorization requests
org.hibernate Log everything (a lot of information, but very useful for troubleshooting)
When developing applications with Hibernate, you should almost always work with debug enabled for the category org.hibernate.SQL, or, alternatively, the property hibernate.show_sql enabled.