Postgres similarity function with spring data - postgresql

Question

I tried to implement a search query in my spring-boot service which utilizes the similarity(text, text) function of postgres.
I got the similarity working in the postgres console, and managed to get it over to my #Repository interface as native query.
It seems to construct the query correctly, but every time I try to execute the query I get
ERROR: function similarity(text, character varying) does not exist
When I try to create the extension again, I get an exception, that this extension is already installed.
What am I missing? Do I need some Spring/JPA magic Object to enable this?
Example entity:
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;
import lombok.Data;
#Entity
#Table(name = "example")
#Data
public class ExampleEntity {
#Id
private String id;
private String textField;
}
Example repository:
import java.util.Set;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Repository;
#Repository
public interface ExampleRepository extends CrudRepository<ExampleEntity, String> {
#Query(nativeQuery = true,
value = "SELECT * FROM example ORDER BY similarity(:searchString)")
List<ExampleEntity> findBySimilarity();
#Query(nativeQuery = true, value = "CREATE EXTENSION pg_trgm")
void createSimilarityExtension();
}
Test code (excluding setup, as it is rather complex):
public void test() {
ExampleEntity r1 = dbUtils.persistNewRandomEntity();
ExampleEntity r2 = dbUtils.persistNewRandomEntity();
ExampleEntity r3 = dbUtils.persistNewRandomEntity();
try {
exampleRepository.createSimilarityExtension();
} catch (InvalidDataAccessResourceUsageException e) {
// always says that the extension is already setup
}
List<ExampleEntity> bySimilarity = exampleRepository.findBySimilarity(r2.getTextField());
for (ExampleEntity entity : bySimilarity) {
System.out.println(entity);
}
}

Answer 1

Turns out I created the extension in the wrong schema while trying out if the extension would work at all.
I then added the extension to my DB-migration script, but would skip it if the extension existed. Therefore my extension was registered for the public schema and did not work in the actual schema my service is using.
So if you have the same problem I had, make sure your extension is created for the correct schema by using:
SET SCHEMA <your_schema>; CREATE EXTENSION pg_trgm;