Redis vs RabbitMQ vs Kafka (Data Structure Comparison)

Yes — Redis main data structure is:

• Hashtable (key → value) stored in RAM

• Very fast lookup: O(1)
• Works like an in-memory dictionary

• Redis = key-value store (like a dictionary / hashmap)

RabbitMQ is NOT a hashtable system.

It is a message queue system.

• FIFO Queue (First In First Out)
• Internally uses queue buffers (Erlang ETS tables + disk storage)

Producer → Exchange → Queue → Consumer

Inside the queue:

• Messages are stored in order (FIFO)
• Stored in memory first, then disk if durable

• RabbitMQ = queue-based message broker
• Not key-value lookup
• You do NOT query messages by key

Kafka is NOT a hashtable and NOT a queue.

It is an append-only distributed log system.

• Append-only log file
• Each topic contains partitions
• Each partition is a sequence of messages

Example:

offset 0 → msg1
offset 1 → msg2
offset 2 → msg3

Producer → Topic → Partition Log → Consumer reads by offset

• Kafka = distributed commit log
• Consumers read using offsets (like file pointers)

• Redis → Dictionary (key-value store)
• RabbitMQ → Waiting line (queue)
• Kafka → Log book (append-only journal)