H2 database usage of external library like apache.commons

Question

I was trying to use H2 Database. I want to call methods in Apache Commons Library i.e. commons-maths3.jar.

H2.bat looks as follows:

@java -cp "commons-math3.jar;h2.jar" org.h2.tools.Console %*

But when accessing the library method with the following:

CREATE ALIAS sd for "org.apache.commons.math3.stat.descriptive.moment.StandardDeviation";

I am getting 90086 error.

Class "org.apache.commons.math3.stat.descriptive.moment" not found; SQL statement: create alias sd for "org.apache.commons.math3.stat.descriptive.moment.StandardDeviation" [90086-193] 90086/90086

Also, please suggest me how to know that a library is accessible to H2 something like DESCRIBE StandardDeviation.

Is there anything I am missing here.

Answer 1

Quote from the H2 manual:

The method name must be the full qualified class and method name, and may optionally include the parameter classes as in java.lang.Integer.parseInt(java.lang.String, int). The class and the method must both be public, and the method must be static. The class must be available in the classpath of the database engine.

^{(Emphasis mine)}

So you need to specify a static method for the alias, not a class name.

But StandardDeviation has no static methods. You need to write a (static) wrapper function (in Java) yourself if you want to use that.