Advantages of Cassandra's masterless architecture
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This document summarizes the advantages and cautions of Cassandra's masterless architecture. The advantages include its peer-to-peer design, automatic data distribution without a single point of failure, and built-in replication. However, cautions are noted since Cassandra is a NoSQL database, which means it has different data modeling than SQL and lacks features like transactions and complex queries. Real-world examples are provided to illustrate Cassandra's data distribution and limited query capabilities.
Advantages of Cassandra's masterless architecture
- 1. Advantages of Cassandra’s masterless architecture Duy Lam @ RD KMS TechCon 2015
- 6. Masterless Architecture Cassandra cluster Background service Web service Application Peer-to-peer Database Automatic Data Distribution Built-in Replication No SPOF A node
- 7. Masterless Architecture Peer-to-peer Database Automatic Data Distribution Built-in Replication partition id name usa_1994 ae12f… The Shawshank Redemption usa_1994 bb2ac… Forrest Gump skorea_2002 31dcc… The Way Home vn_2015 890af… Jackpot 2 usa_1994 ae… The Sha.. usa_1994 bb… Forrest.. 1 skorea_2002 31… The Way … 3 vn_2015 89… Jackpot Cassandra cluster CREATE TABLE movie ( partition text , id uuid, name text )
- 8. Masterless Architecture Peer-to-peer Database Automatic Data Distribution Built-in Replication partition id name (A) usa_1994 ae12f… The Shawshank Redemption usa_1994 bb2ac… Forrest Gump (B) skorea_2002 31dcc… The Way Home (C) vn_2015 890af… Jackpot 2 1 3 Cassandra cluster CREATE TABLE movie ( partition text , id uuid, name text ) (B) (A’) (C’) (A) (B’) (C’) (C) (A’) (B’)
- 13. Cautions Cassandra is from NoSQL family So ?
- 14. Cautions Cassandra is from NoSQL family So Different data modeling (try to google “nosql data modeling”) No Atomicity for multiple tables (or “documents”) no transaction Not good at complex query (group by, having, like, >=, etc.)
- 15. Cautions CREATE TABLE movie ( partition text, id uuid, name text, released_year int, country text, PRIMARY KEY (partition, id) ) Limited query capability in Cassandra SELECT * FROM movie WHERE release_year < 2000 name LIKE “Star Trek” name IN ( “Tangled”, “Frozen” ) name = “Inside Out” and year = 2015 length = null length = 120 OR release_year = 2015 UPDATE movie SET length=95 WHERE partition = “vn” AND id = 10 INSERT INTO movie(partition, id, length) VALUES(“usa”, 15, 120) (1) (2) (3) (4) (5) (6)
- 16. Cautions CREATE TABLE movie ( partition text, id uuid, name text, released_year int, country text, PRIMARY KEY (partition, id) ) Limited query capability in Cassandra SELECT * FROM movie WHERE release_year < 2000 name LIKE “Star Trek” name IN ( “Tangled”, “Frozen” ) name = “Inside Out” and year = 2015 length = null length = 120 OR release_year = 2015 UPDATE movie SET length=95 WHERE partition = “vn” AND id = 10 INSERT INTO movie(partition, id, length) VALUES(“usa”, 15, 120) (1) (2) (3) (4) (5) (6)
- 17. References DataStax Cassandra Tutorials https://www.youtube.com/playlist?list=PL3E5AC388940EEC0A (thanks to Provision feature) Launch Cassandra clustering system at http://bit.ly/kms-techcon2015-cassandra-demo
- 18. Take Away Masterless Architecture – Peer-to-peer Database – Automatic Data Distribution – Built-in Replication Cautions – Cassandra is from NoSQL family – Limited query capability
- 19. THANKS YOU
Editor's Notes
- #4: Open source, backed by big sponsor, commercial use Hosted by any platform A company provides many things around Cassandra (documentation, tools, etc.) both free and commercial Note: products using Cassandra listed in slide are more about user-generated content
- #6: 03 characteristic make Cassandra becoming preferable choice for Big Data
- #7: Eliminate SPOF and gain (single point of failure) App can connect to another node if the current node is shutdown Processing capability is spread out
- #8: Partitioner: a function for deriving a token representing a row from its partition key (typically by hashing). A partitioner determines how data is distributed across the nodes in the cluster (including replicas) Cassandra offers the following partitioners: (from Cassandra v1.2+) Murmur3Partitioner (default): uniformly distributes data across the cluster based on MurmurHash (better than MD5 in term of distribution purpose) hash values. RandomPartitioner: uniformly distributes data across the cluster based on MD5 hash values. ByteOrderedPartitioner: keeps an ordered distribution of data lexically by key bytes
- #9: Replicate factor: the total number of replicas across the cluster. A replication factor of 1 means that there is only one copy of each row on one node Replication strategy: a replication strategy determines which nodes to place replicas on
- #10: Summarize things
- #11: Peer-to-peer High Availability Data Distribution Scalability Replication Fault Tolerance
- #12: Prepare Start guest OS: vagrant up Launch 5 terminal and remote to guest OS in all of them. From now on, below commands are executed in remote SSH terminals Launch Cassandra seed node. When it’s fully starting, launch remaining Cassandra nodes Explain setup.cql file Setup schema and seed data: $ ~/apps/cassandra/bin/cqlsh -f ~/provision/setup.cql High Availability Insert new row in node2 (127.0.0.2): $ ~/apps/cassandra/bin/cqlsh -e "USE techcon2015; INSERT INTO participant(department, employee_id, name) VALUES (‘Delivery', 100, 'Nguyen Van An');" 127.0.0.2 See new row in seed node (127.0.0.4): $ ~/apps/cassandra/bin/cqlsh -e "USE techcon2015; select * from participant;" 127.0.0.4 Data is available on any node Fault Tolerance Show the node status: $ ~/apps/cassandra/bin/nodetool status (explain the status and state) Shutdown node2 (127.0.0.2) Show the node status again, indicate the Down status Show that data is still available: $ ~/apps/cassandra/bin/cqlsh -e "USE techcon2015; select * from participant;" 127.0.0.x (x is the other alive IP) Insert new row in seed node (127.0.0.4): $ ~/apps/cassandra/bin/cqlsh -e "USE techcon2015; INSERT INTO participant(department, employee_id, name) VALUES (‘Delivery', 200, 'Nguyen Van Chau');" 127.0.0.4 See new row in seed node (127.0.0.4): $ ~/apps/cassandra/bin/cqlsh -e "USE techcon2015; select * from participant;" 127.0.0.x (x is the other alive IP) No downtime for disconnected node Scalability Show the node status: $ ~/apps/cassandra/bin/nodetool status Remove node 127.0.0.2: $ ~/apps/cassandra/bin/nodetool -h 127.0.0.1 -p 7182 decommission (1782 is node2 jmx port) Show the node status again (indicate node removed): $ ~/apps/cassandra/bin/nodetool status Shutdown node 127.0.0.2 Restart node 127.0.0.2 to join again Cluster can be effortlessly reduced (or increased)
- #15: google term “nosql data modeling” to see more explanation No transaction (commit, fallback) (from experience in Cassandra and mongo)