Make H2 Log Via SLF4J

If you want your in-memory H2 database to log via SLF4J so you can control its logging output using your logging framework of choice, add this canonical string to your JDBC URL:


The actual property you are setting in this case is the INIT property.  Here, you have set it to be equal to exactly one statement.  You can of course set it to be equal to several statements:


The examples above are canonical strings, free of escape characters.  If you are setting these inside a Java String you’ll need to escape things properly.  Here’s a sample JDBC URL written as a double-quoted Java String that makes H2 log using SLF4J and runs some DDL on every connection:

"jdbc:h2:mem:chirp;INIT=SET TRACE_LEVEL_FILE=4\\;RUNSCRIPT FROM 'classpath:foo.ddl'"

Note the double backslashes: the first backslash escapes the next one, which, in turn, escapes the semicolon, because the semicolon is used as a delimiter in the actual JDBC URL itself.

The important thing in all of these cases is that SET TRACE_LEVEL_FILE=4 must come first in the INIT property value.


The maven-ear-plugin and the ear packaging type and why several goals get run

When building a Maven artifact of type ear, the ear packaging type is invoked.

The maven-ear-plugin replaces the maven-jar-plugin at this point, so it is as though you included it in your pom.xml.

The generate-application-xml goal binds by default to the generate-resources phase.

The ear goal binds by default to the package phase.

So at the end of the day by declaring a packaging type of ear, you cause two goals—not one—to be run.