Streaming #

You can streaming write to the Append table in a very flexible way through Flink, or through read the Append table Flink, using it like a queue. The only difference is that its latency is in minutes. Its advantages are very low cost and the ability to push down filters and projection.

Automatic small file merging #

In streaming writing job, without bucket definition, there is no compaction in writer, instead, will use Compact Coordinator to scan the small files and pass compaction task to Compact Worker. In streaming mode, if you run insert sql in flink, the topology will be like this:

Do not worry about backpressure, compaction never backpressure.

If you set write-only to true, the Compact Coordinator and Compact Worker will be removed in the topology.

The auto compaction is only supported in Flink engine streaming mode. You can also start a compaction job in flink by flink action in paimon and disable all the other compaction by set write-only.

Streaming Query #

You can stream the Append table and use it like a Message Queue. As with primary key tables, there are two options for streaming reads:

By default, Streaming read produces the latest snapshot on the table upon first startup, and continue to read the latest incremental records.
You can specify scan.mode or scan.snapshot-id or scan.timestamp-millis or scan.file-creation-time-millis to streaming read incremental only.

Similar to flink-kafka, order is not guaranteed by default, if your data has some sort of order requirement, you also need to consider defining a bucket-key, see Bucketed Append