pyflink.table.expressions.current_watermark#
- current_watermark(rowtimeAttribute) Expression[source]#
Returns the current watermark for the given rowtime attribute, or NULL if no common watermark of all upstream operations is available at the current operation in the pipeline.
The function returns the watermark with the same type as the rowtime attribute, but with an adjusted precision of 3. For example, if the rowtime attribute is TIMESTAMP_LTZ(9), the function will return TIMESTAMP_LTZ(3).
If no watermark has been emitted yet, the function will return NULL. Users must take care of this when comparing against it, e.g. in order to filter out late data you can use
WHERE CURRENT_WATERMARK(ts) IS NULL OR ts > CURRENT_WATERMARK(ts)
Added in version 1.12.0.