Structured Streaming supports three output modes:

Append: Writes only new rows since the last trigger.

Update: Writes only updated rows.

Complete: Writes the entire result table after every trigger execution.

For aggregations like groupBy().count(), only complete mode outputs the entire table each time.

Example:

aggDF.writeStream \

outputMode("complete") \

format("console") \

start()

Why the other options are incorrect:

A: “AGGREGATE” is not a valid output mode.

C: “REPLACE” does not exist.

D: “APPEND” writes only new rows, not the full table.