presto-hive/src/main/java/io/prestosql/plugin/hive/metastore/file/FileHiveMetastore.java/FileHiveMetastore/verifyDatabaseNotExists
class FileHiveMetastore:    private void verifyDatabaseNotExists(String databaseName)
    {
        if (getDatabase(databaseName).isPresent()) {
            throw new SchemaAlreadyExistsException(databaseName);
        }
    }