private void closeDatabase() {
        this.opened = false;
        try {
            IOUtils.close(defaultTable, confTable, environment);
        } catch (IOException e) {
            // ignore
        }
        this.defaultTable = null;
        this.confTable = null;
        this.environment = null;

    }
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