[Improve][doc][txn] add brokerDeduplicationEnabled=true to enable transaction deduplication
@@ -20,21 +20,27 @@ This section provides an example of how to use the transaction API to send and r
2. Enable transaction.
- Change the configuration in the `broker.conf` file.
+ Change the configuration in the `broker.conf` or `standalone.conf` file.
```
+ //mandatory configuration, used to enable transaction coordinator
transactionCoordinatorEnabled=true
+
+ //mandtory configuration, used to create systemTopic used for transaction buffer snapshot
systemTopicEnabled=true
- ```
- If you want to enable batch messages in transactions, follow the steps below.
+ ```
- Set `acknowledgmentAtBatchIndexLevelEnabled` to `true` in the `broker.conf` or `standalone.conf` file.
+ * If you want to acknowledge batch messages in transactions, set `acknowledgmentAtBatchIndexLevelEnabled` to `true` in the `broker.conf` or `standalone.conf` file.
```
acknowledgmentAtBatchIndexLevelEnabled=true
```
+ * If you want to guarantee exactly-once semantics, you need to enable [message deduplication](cookbooks-deduplication.md).
+ You can enable message deduplication at the broker level, the namespace level, or the topic level according to your needs.
+
+
3. Initialize transaction coordinator metadata.
The transaction coordinator can leverage the advantages of partitioned topics (such as load balance).
