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Kafka's idempotent producer makes retries safe by letting brokers discard duplicate batches. Here's how PID and sequence numbers work, what the guarantee doesn't cover, and how to verify it.
When a Vagrant machine fails to provision due to a transient network glitch or a synced‑folder mount error, the provisioner may be retried automatically. If the provisioner is configured with run: 'always' , Vagrant will execute it on every retry, potentially causing duplicate writes such as appending timestamps or installing packages twice. Setting run: 'on
Goal Maintain exactly‑once semantics across all Structured Streaming sinks during retries, avoiding duplicate writes when a task restarts. Current Landscape Apache Spark relies on checkpointing and write‑ahead logs to recover from failures. Exactly‑once guarantees are only available for sinks that implement idempotent writes (Kafka, Delta Lake, HDFS/Parquet)