A look at how the scalable storage architecture of Apache Pulsar makes it possible to retain and access any length of event or message history in Pulsar.

1. Infinite* Topic Backlogs
with Apache Pulsar
Ivan Kelly
@ivankelly

2. Peter Norvig - Google
We don’t have better algorithms than anyone else; we
just have more data

3. An example system
Stream
Processing
Engine
Model
User
events
Serving
System
Songs user has
listened to
Recommendation algorithm
User listening model
Recommended songs

4. Stream
Processing
Engine
Partial Model
Live User
events
Serving
System
Historical
User Events
Batch
Processing
Engine
Partial Model
Combined
Model

5. Stream
Processing
Engine
Live User
events
Serving
System
Partial Model
Historical
User Events
Batch
Processing
Engine
Partial Model
Combined
Model
Model

6. Apache Pulsar
Messaging System
Pubsub and queuing
Strong guarantees on message persistence
Unlimited topic backlog size
Tiered Storage
Lightweight compute
SQL interface available

7. Anatomy of a topic backlog
A B C
Broker
Client produces message
Broker acknowledges
message to client
Broker writes message
to topic backlog
D E F G
Topic Backlog

8. Anatomy of a topic backlog
A B C D E F G
Closed Open
Topic Backlog

9. A B C
Storage 2
Storage 3
Storage 1

10. Storage layer
Storage 1 Storage 2 Storage 3
Serving layer
Broker 1 Broker 2

11. Storage layer
Add nodes to add storage
Topic Backlog

12. Mirroring
1/n = 0.5 space efficiency
Tolerates n - 1 = 1 failures
Gets worse with more replicas
Striping with parity
1 - 1/n = 0.833 space efficiency
Tolerates 1 failure
Space efficiency increases with nParity

13. Tiered Storage
Broker
Client writes
messages
Storage nodes
Long-term storage
Client reads
messages

14. 1. Pulsar topic metadata updated with potential new location
2. All messages from segment copied to data object in long-term storage
3. Copying process tracks message offsets at defined interval
4. Offsets written to index object in long-term storage
5. Pulsar topic metadata updated with offload completed status
6. Original segment deleted from Pulsar storage after grace period

15. Available long-term storage options
Since v2.1.0
Since v2.2.0
Implemented but not merged

16. Demo
Bloom
Filter
Function
T1 T2 T3
Q1 Q2 R1 R2
T4
Twitter topic
Query topic
Result topic

17. Querying massive backlogs
Pulsar provides SQL interface from v2.2.0
Based on PrestoDB
Table schema from topic schema
Queries data at rest

18. Long-term
storage
Broker
StorageStorageStorageStorageStorageStorage
BrokerBrokerBrokerBroker
Presto
Worker
Presto
Worker
Presto
Worker
Presto
client
Presto
Coord

19. Demo

20. Apache Pulsar
• Unlimited backlog size
• Offload older data to cheaper storage
• Query with an SQL interface
Other uses cases for massive backlogs
• CQRS Event sourcing
• Data marts
• Audit logs
• Security logs

21. Blog: https://streaml.io/blog
@streamlio @ivankelly