Filter and map operations in Kafka - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the filter operation do in Kafka Streams?

The filter operation keeps only the records that match a given condition, removing all others from the stream.

beginner

What is the purpose of the map operation in Kafka Streams?

The map operation transforms each record in the stream by applying a function to change its key and/or value.

intermediate

How do filter and map operations work together in a Kafka Streams pipeline?

First, filter removes unwanted records, then map changes the remaining records to a new form for further processing.

beginner

In Kafka Streams, what type of function do you pass to the filter method?

You pass a predicate function that returns true for records to keep and false for records to discard.

beginner

What does the map function return for each record in Kafka Streams?

It returns a new key-value pair, which can be different from the original record's key and value.

What does the filter operation do in Kafka Streams?

A Keeps records that meet a condition

B Changes the key and value of records

C Joins two streams

D Saves records to a database

The filter operation keeps only records that satisfy the given condition.

What does the map operation do in Kafka Streams?

A Deletes records from the stream

B Filters records based on a condition

C Transforms each record's key and value

D Splits the stream into two

Map transforms each record by applying a function to change its key and/or value.

Which function type is passed to filter in Kafka Streams?

A A function that joins streams

B A function returning a boolean

C A function returning a new key-value pair

D A function that writes to a topic

Filter requires a predicate function that returns true or false.

What happens if a record does not pass the filter condition?

A It is kept in the stream

B It is sent to a different topic

C It is transformed by map

D It is removed from the stream

Records that do not meet the filter condition are removed from the stream.

In Kafka Streams, what is the output of the map operation?

A A stream with transformed records

B A filtered stream

C A joined stream

D A saved state store

Map outputs a stream where each record is transformed to a new key-value pair.

Explain how you would use filter and map operations together in a Kafka Streams application.

Think about cleaning data first, then changing it.

Describe the type of function you pass to the filter operation and what it returns.

It's like a yes/no question for each record.