private void openDatabase() throws DatabaseException, IOException {
        if (this.opened) {
            return;
        }
        final File databaseHomeDir = new File(homePath);
        FileUtils.forceMkdir(databaseHomeDir);
        EnvironmentConfig environmentConfig = new EnvironmentConfig();
        environmentConfig.setTransactional(true);
        environmentConfig.setAllowCreate(true);
        DatabaseConfig databaseConfig = new DatabaseConfig();
        databaseConfig.setAllowCreate(true);
        databaseConfig.setTransactional(true);
        this.environment = new Environment(databaseHomeDir, environmentConfig);
        this.defaultTable = this.environment.openDatabase(null, DEFAULT_DATABASE_NAME, databaseConfig);
        this.confTable = this.environment.openDatabase(null, CONF_DATABASE_NAME, databaseConfig);
        this.opened = true;
    }
First log index and last log index key in configuration column family.
jraft-extension/bdb-log-storage-impl/src/main/java/com/alipay/sofa/jraft/storage/impl/BDBLogStorage.java