Question 13 of 50
What is a Topic?
Question
"What is a Topic in Kafka?"
What the interviewer wants to assess
Whether you distinguish the logical abstraction (topic) from the actual physical structure (partitions) — a common mistake is treating "topic" as if it were the log itself, when it's actually split into independent partitions.
Resposta rápida
Topic is the logical name under which related events are published and consumed — for example,
pagamentos.aprovados. Physically, a topic is split into one or more partitions, which are the ordered
logs where the data actually lives.
Resposta nível Sênior
A topic has no schema imposed by Kafka itself — the schema, when it exists, is the responsibility of a layer like the Schema Registry. What Kafka guarantees about a topic is the split into partitions and delivery order within each one — not across different partitions of the same topic. When creating a topic, the relevant decisions are the number of partitions (parallelism, Chapter 4), the replication factor (availability, Chapter 5), and the retention policy (Chapter 8) — the topic itself is just the name that ties those decisions together.
In-depth explanation
See "Topic" in Chapter 3.
Exemplo financeiro
The boletos.emitidos topic might have 8 partitions, replication factor 3, and 30 days of retention —
three independent design decisions, all tied to the same logical topic name that producers and consumers
reference in code.
"A Kafka topic is like a database table"
The analogy helps convey that a topic groups related data, but it breaks down around ordering: a table normally has no notion of "order guaranteed only for a subset of rows" — a Kafka topic has exactly that characteristic, because of partitions.
Pode vir a seguir
Likely follow-ups: "what is a Partition?" and "why do Partitions exist?".
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