Watermark (data)
A tracking marker that records the last successfully processed record in a data stream. Used in incremental sync workflows the watermark (e.g., a timestamp or record ID) ensures the next run picks up from where the last one stopped, not from the beginning.
Expert insight
A watermark (a marker tracking how far a pipeline has processed, like "everything up to this timestamp") needs to advance conservatively, if it advances past records that arrived late (out of order), those late records get permanently skipped, a real risk for any source where events aren't guaranteed to arrive in strict time order.
In a real workflow
The timestamp of the last processed record is stored as a watermark for the next incremental run.
Common mistakes
- Updating the watermark before processing succeeds.
- Clock skew causing missed records.
Complexity level
Requires some familiarity with automation concepts.
Related terms
Incremental sync
Syncing only the records that have changed since the last sync run, rather than …
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