Data Source 和 Sink 的容错保证

Sink	Guarantees	Notes
HDFS BucketingSink	exactly once	Implementation depends on Hadoop version
Elasticsearch	at least once
Kafka producer	at least once/ exactly once	exactly once with transactional producers (v 0.11+)
Cassandra sink	at least once / exactly once	exactly once only for idempotent updates
AWS Kinesis Streams	at least once
File sinks	at least once
Socket sinks	at least once
Standard output	at least once
Redis sink	at least once