Databricks Databricks-Certified-Associate-Developer-for-Apache-Spark-3.5 Exam With Confidence Using Practice Dumps

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.

To exclude sensitive (PII) columns from a DataFrame, the easiest method is to use the .drop() function with the list of column names to remove.

Correct syntax:

df_user_non_pii = df_user.drop("name", "email", "birthdate")

This creates a new DataFrame containing all remaining columns.

Why the other options are incorrect:

B: .dropFields() is not valid for standard DataFrames — it’s used for struct fields only.

C: .select() would keep only PII columns, not remove them.

D: .remove() does not exist in Spark DataFrame API.

In Structured Streaming, checkpoints store state information (offsets, progress, and metadata) needed to resume a stream after a failure or restart.

Correct usage:

Set the checkpointLocation option when writing the streaming output:

streaming_df.writeStream \

format("delta") \

option("checkpointLocation", "/path/to/checkpoint/dir") \

start("/path/to/output")

Spark uses this checkpoint directory to recover progress automatically and maintain exactly-once semantics.

Why the other options are incorrect:

A/D: recoveryLocation is not a valid Spark configuration option.

B: Checkpointing must be configured in writeStream, not during readStream.