visortelle commented on code in PR #712: URL: https://github.com/apache/pulsar-site/pull/712#discussion_r1508010705
########## docs/txn-advanced-features.md: ########## @@ -37,10 +37,34 @@ If you want to enable authentication with transactions, follow the steps below. 2. [Configure authentication](security-overview/#authentication) in a Pulsar client. +## Select transaction isolation level + +In order to enhance the flexibility of pulsar transactions, pulsar transactions support two different isolation levels, the default isolation level is Read Committed: +- READ_COMMITTED, Consumer can only consume all transactional messages which have been committed. +- READ_UNCOMMITTED, Consumer can consume all messages, even transactional messages which have been aborted. + +For different scenarios, they use different subscriptions and choose different isolation levels. One needs transaction, one does not. In general, multiple subscriptions of the same topic do not all +require transaction guarantees. Some want low latency without the exact-once semantic guarantee(like Real-time monitoring system), and some must require the exactly-once guarantee(like Business Processing System). +Users can freely choose different isolation levels according to different scenarios. + +Note that this is a subscription dimension configuration, and all consumers under the same subscription need to be configured with the same IsolationLevel. + +This example selects READ_UNCOMMITTED Isolation level in the consumer builder: Review Comment: ```suggestion This example selects `READ_UNCOMMITTED` Isolation level in the consumer builder: ``` -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
