Module watermark_udf 

Watermark UDF for current watermark access Watermark UDF for DataFusion integration

Provides a watermark() scalar function that returns the current watermark timestamp from Ring 0 via a shared Arc<AtomicI64>.

The watermark represents the boundary below which all events are assumed to have arrived. Queries can use WHERE event_time > watermark() to filter stale data.

Structs

WatermarkUdf

Scalar UDF that returns the current watermark timestamp.

Constants

NO_WATERMARK

No-watermark sentinel value. When the atomic holds this value, watermark() returns NULL.