Always prompts that the language pljava does not exist

[Houtx]

postgresql 15、java 11、pljava1.6.6

Always prompts that the language pljava does not exist!

[jcflack]

Hello,

I cannot read the localized messages, but from the SQLSTATE 42710 in the last screenshot, I infer it is saying the extension has already been created. Just a few comments:

• there is no need for the pljava.classpath setting in postgresql.conf. PL/Java has not even had a variable by that name since a rather old version, so that line has no effect.
• the extension does not create a language named pljava. It creates two languages by default, one named java and one named javaU. So try simply LANGUAGE java instead of LANGUAGE pljava.
• it is not possible to simply put Java source, like return "Hello from Java!";, into the AS string. The AS string must refer to a public static method in a Java class that you have already compiled, and loaded into PostgreSQL in a jar file.
• The best way to write the CREATE FUNCTION declaration properly is to let the Java compiler do it, using annotations you place on the method in the Java source.

There is a step-by-step "Hello, world"-style example here:

https://tada.github.io/pljava/use/hello.html

I am sorry that it is only available in English.

[Houtx]

@jcflack I found that the previous installation method was wrong, and I have successfully reinstalled pljava1.6.6 into postgresql15. Then I want to package a jar according to the sample program, but pljava-api cannot be found in maven. What is the reason or from which repository can I download dependency?

[jcflack]

Building and uploading the api jar to an online repo has been on the wish list for a long time, but still needs attention. One complication is coordinating the use of the org.postgresql space, which the PL/Java project doesn't control.

But if you have installed PL/Java 1.6.6 on your PostgreSQL server, you already have the pljava-api-1.6.6.jar on your server, in $(pg_config --sharedir)/pljava and you can copy it from there, adding to your local Maven repository if that is what's most convenient.

Or, of course, if you build PL/Java from source using Maven, the API jar ends up in your local repository as a matter of course.

[Houtx]

Building and uploading the api jar to an online repo has been on the wish list for a long time, but still needs attention. One complication is coordinating the use of the org.postgresql space, which the PL/Java project doesn't control.

But if you have installed PL/Java 1.6.6 on your PostgreSQL server, you already have the pljava-api-1.6.6.jar on your server, in $(pg_config --sharedir)/pljava and you can copy it from there, adding to your local Maven repository if that is what's most convenient.

Or, of course, if you build PL/Java from source using Maven, the API jar ends up in your local repository as a matter of course.

Thanks, following this program will solve it!