So far, we have talked about the architecture of Kafka, Klosters, and you know that every door consists
of a Kafka brokers and Zwicky Prospero's also there are producers and consumers, but there are basically
messages are stored at every broker.
For that.
There is a special entity called the topic, and every topic has its own unique name and they must be
unique across Kafka.
Kloster and every message inside of the topic has a specific number called Offset, and this number
is assigned to every message when it arrives to a specific broker.
And when times go by, every producer may append messages only to the end of the log.
For example, here you see that the new messages may be added after a message with the offset button,
and you are not able to insert a message, for example, here between messages two and three does not
possible.
And that means that every number is immutable and every log record in Breuker is immutable and you are
not able to change it.
But on either side, the broker may delete old records or log records that were expired.
And by default, this period, gold log retention period is set to one hundred six to eight hours or
seven days.
And that means that the by default, again, by default, every broker will delete all messages that
are older than seven days.
Of course, the retention policy is subject to change if you need.
So short summary is following.
Every topic has its own unique name and every message has its own number of set and new messages that
arrive could be appended only after existing messages.
You are not able to insert any messages before previous messages and old messages could be deleted automatically
if the retention period has expired.
And one more important note is every broker does not care about consumers.
It means that if Thoros Kafka messages independent of consumers that they may read or may not read messages
from the log.
It does not matter for Kafka at all.
Its job is just to receive your messages and append them at the end of previous messages.
So that's all for this year and next.
Let me quickly explain the structure of each message, so I'll see you next.
My bye.