| name | flink |
| description | Apache Flink stream processing expertise for stateful computations over bounded and unbounded streams. Use when the user mentions Flink, Flink SQL, Table API, DataStream API, CDC, Kafka-to-Flink pipelines, checkpoints, savepoints, watermarks, windows, Flink Kubernetes Operator, or Flink integrations with Iceberg, Paimon, or Fluss. |
Apache Flink Data Streaming Expert
Use this skill for production Flink architecture, operations, SQL/DataStream implementation, upgrade planning, and lakehouse streaming integrations.
Current Facts
- Current Flink line: 2.2.x. Downloads include Apache Flink 2.2.1, while the site still labels 2.2.0 as the latest stable line.
- Maintained 2.x patch lines: 2.2.1, 2.1.2, 2.0.2.
- 1.x maintenance line: 1.20.4. Use this as the 1.x migration baseline unless the project is pinned elsewhere.
- Kubernetes Operator: 1.15.0, compatible with Flink 2.2.x, 2.1.x, 2.0.x, 1.20.x, and 1.19.x.
- Flink CDC: 3.6.0, with artifacts for Flink 1.20.x and 2.2.x.
- Java: Flink 2.x requires Java 11+; Java 17 is the practical default for new deployments.
Critical 2.x Notes
- DataSet API removed; use DataStream, Table API, or SQL.
- Scala DataStream/DataSet APIs removed from the core distribution.
- SourceFunction/SinkFunction and Sink V1 patterns are obsolete; prefer Source/Sink V2 connectors.
flink-conf.yaml was replaced by standard YAML config.yaml in Flink 2.x.- Per-job deployment mode was removed; use Application mode or Kubernetes Operator patterns.
- Validate savepoint compatibility carefully before 1.x to 2.x migrations.
How To Use
- Classify the request: SQL/Table API, DataStream, deployment, operations, upgrade, CDC, or lakehouse sink/source.
- For new greenfield work, prefer Flink 2.2.x plus current connector artifacts.
- For migration work, identify the exact source version, connector versions, state backend, and savepoint strategy before recommending commands.
Production Defaults
- Enable checkpointing for streaming jobs and set explicit checkpoint storage.
- Use savepoints for planned upgrades and topology changes.
- Use watermarks and allowed lateness deliberately; make event-time assumptions visible.
- Monitor checkpoint duration, alignment time, backpressure, restart count, and state size.
- Prefer the Kubernetes Operator for long-running production jobs on Kubernetes.
- Use Iceberg/Paimon/Fluss connectors only at versions compatible with the selected Flink line.
Update Checklist
- Recheck Flink downloads for core, CDC, connector, and Kubernetes Operator versions.
- Update Helm/doc URLs when operator versions change.
