The Flink/Delta Connector, introduced in Delta Connectors 0.4.0, lets Apache Flink write Parquet data files and commit them atomically to Delta Lake tables using Flink's DataStream API, supporting both batch and streaming workloads. The connector preserves Flink's exactly-once semantics through checkpoint-based commits, using components like DeltaWriter, DeltaCommittable, DeltaCommitter, and DeltaGlobalCommitter to manage file states from in-progress to finished. It currently supports append-only writes for Flink >= 1.12, with reading support, additional write modes (overwrite, upsert), and Table API/SQL integration planned for future releases.
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Apache Flink - Distributed processing engine for stateful computationsDelta Lake - Open Source Data Lake Storage StandardsNative Flink Delta Lake ConnectorArchitectureWhat’s next?Questions this post answers
How do I write data from Apache Flink to a Delta Lake table?
Use the Flink/Delta Connector introduced in Delta Connectors 0.4.0, which provides a DeltaSink built on Flink's DataStream API. It writes Parquet data files and commits them atomically to Delta tables in append mode, supporting both batch and streaming pipelines for Flink versions 1.12 and above. daily.dev surfaces connector releases like this for teams wiring Flink into their data lake.
Does the Flink Delta Sink guarantee exactly-once processing?
Yes, as long as the Flink pipeline restarts from checkpoint information. The connector writes data idempotently through components called DeltaWriter, DeltaCommitter, and DeltaGlobalCommitter, which track files through in-progress, pending, and finished states. Without a valid checkpoint restart, exactly-once guarantees no longer apply. Engineers building fault-tolerant streaming pipelines can track connector details like this via daily.dev.
Can the Flink Delta connector read from Delta Lake tables or only write to them?
Only writing is supported currently, through the DeltaSink component. Reading Delta tables from Flink is still in progress, tracked as a separate feature, and support for other write modes like overwrite and upsert, plus the Flink Table API and SQL integration, are planned for upcoming releases. daily.dev helps engineers evaluating Flink and Delta Lake keep tabs on connector capability gaps.