@Override
    public boolean appendEntry(LogEntry entry) {
        if (entry == null) {
            return false;
        }
        this.readLock.lock();
        Transaction txn = null;
        try {
            checkState();
            DatabaseEntry key = getKeyDatabaseEntry(entry.getId().getIndex());
            DatabaseEntry value = toDatabaseEntry(entry);
            txn = beginTransaction();
            if (entry.getType() == EntryType.ENTRY_TYPE_CONFIGURATION) {
                this.confTable.put(txn, key, value);
            }
            this.defaultTable.put(txn, key, value);
            txn.commit();
            syncIfNeed();
            return true;
        } catch (DatabaseException e) {
            LOG.error("Fail to append entry {}.", entry, e);
            if (txn != null) {
                txn.abort();
            }
        } finally {
            this.readLock.unlock();
        }
        return false;
    }
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