- Can have multiple brokers on same machine. Each broker has an Broker Id
- Messages in Kafka are variable size byte array. Can use any data format as per need
- No size limit on message (Optimal: KBs, Practical: 1 MB)
- Retails data even if not read by consumer. Data retained for 7 days/ 1 GB (Default)
- No limit on topics but works best with few large topics
- The commit logs are append only we cannot delete/ modify an message
- Topics are broken up into ordered commit logs called partitions
- Each message in a partition is assigned a sequential id called as offset
- Writes to partition are sequential in order (Reduces no. of hard disk seeks)
- Messages can be read either from an offset or from the beginning
IMPORTANT
- No of replications = No. of brokers on the cluster
- 1 consumer can consume from 1 partition at a time (Multiple consumers cannot access the same partition)
- We can have multiple partitions on the same cluster